Adaptive current regulation for solid state lighting

ABSTRACT

Exemplary embodiments provide an apparatus, system and method for power conversion to provide power to solid state lighting, and which may be coupled to a first switch, such as a dimmer switch. An exemplary system for power conversion comprises: a switching power supply comprising a second, power switch; solid state lighting coupled to the switching power supply; a voltage sensor; a current sensor; a memory; a first adaptive interface circuit to provide a resistive impedance to the first switch and conduct current from the first switch in a default mode; a second adaptive interface circuit to create a resonant process when the first switch turns on; and a controller to modulate the second adaptive interface circuit when the first switch turns on to provide a current path during the resonant process of the switching power supply.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and is a continuation-in-part of U.S.patent application Ser. No. 11/655,558, filed Jan. 19, 2007, inventorsAnatoly Shteynberg et al., entitled “Impedance Matching Circuit forCurrent Regulation of Solid State Lighting,” now U.S. Pat. No.7,656,103, which claims the benefit of U.S. Provisional PatentApplication No. 60/760,157, filed Jan. 20, 2006, inventors AnatolyShteynberg et al., entitled “Off-Line LED Driver with Phase Modulation,”both of which are commonly assigned herewith, the contents of which areincorporated herein by reference with the same full force and effect asif set forth in their entireties herein, and with priority claimed forall commonly disclosed subject matter.

FIELD

The present disclosure in general is related to power conversion, andmore specifically, to a system, apparatus, and method for supplyingpower to solid state lighting devices, such as for providing power tolight-emitting diodes (“LEDs”).

BACKGROUND

A wide variety of off-line power supplies for providing power to LEDsare known. Many of these power supplies (i.e., drivers) are effectivelyincompatible with the existing lighting system infrastructure, such asthe lighting systems typically utilized for incandescent or fluorescentlighting, such as infrastructure generally utilizing phase-modulating“dimmer” switches to alter the brightness or intensity of light outputfrom incandescent bulbs. Accordingly, replacement of incandescent lampsby LEDs is facing a challenge: Either do a complete rewiring of thelighting infrastructure, which is expensive and unlikely to occur, ordevelop new LED drivers compatible with commercially available andalready installed dimmer switches. In addition, as many incandescent orother lamps will likely remain in any given lighting environment, itwould be highly desirable to enable LEDs and incandescent lamps to beable to operate in parallel and under common control.

Incandescent lamps and LEDs can be connected to a common lamp power bus,with the light output intensity controlled using a composite waveform,having two power components. This is complicated, requires excessivelymany components to implement, and is not particularly oriented to AC(alternating current) utility lighting.

An off-line LED driver with a power factor correction capability hasbeen described. When coupled with a dimmer, however, its LED regulationis poor and it does not completely support stable operation of thedimmer in the full range of output loads, specifically when bothincandescent and LED lamps are being used in parallel.

FIG. 1 is a circuit diagram of a prior art current regulator 50connected to a dimmer switch 75 which provides phase modulation. FIG. 2is a circuit diagram of such a prior art (forward) dimmer switch 75. Thetime constant of resistor 76 (RI) and capacitor 77 (C1) control thefiring angle “α” (illustrated in FIG. 3) of the triac 80. The diac 85 isused to maximize symmetry between the firing angle for the positive andnegative half cycles of the input AC line voltage (35). Capacitor 45(C2) and inductor 40 (L1) form a low pass filter to help reduce noisegenerated by the dimmer switch 75. A triac 80 is a switching deviceeffectively equivalent to reverse parallel Silicon Controlled Rectifiers(SCRs), sharing a common gate. The single SCR is a gate-controlledsemiconductor that behaves like a diode when turned on. A signal at thegate (70) is used to turn the triac 80 on, and the load current is usedto hold or keep the triac 80 on. Thus, the gate signal cannot turn anSCR off and it will remain on until the load current goes to zero. Atriac 80 behaves like an SCR but conducts in both directions. Triacshave different turn-on thresholds for positive and negative conduction.This difference is usually minimized by using a diac 85 coupled to thegate 70 of the triac 80 to control the turn-on voltage of the triac 80.

Triacs 80 also have minimum latching and holding currents. The latchingcurrent is the minimum current to turn on the triac 80 when given asufficient gate pulse. The holding current is the minimum current tohold the triac 80 in an on-state once conducting. When the current dropsbelow this holding current, the triac 80 will turn off. The latchingcurrent is typically higher than the holding current. For dimmerswitches that use triacs, capable of switching 3 to 8 A for example, theholding and latching currents are on the order of 10 mA to about 70 mA,also for example and without limitation.

The firing angle (α) of the triac 80 controls the delay from the zerocrossing of the AC line, and is theoretically limited between 0° and180°, with 0° equating to full power and 180° to no power delivered tothe load, with an exemplary phase-modulated output voltage illustratedin FIG. 3 (as a “chopped” sinusoid). A typical dimmer switch, forexample, may have minimum and maximum a values of about 25° and 155°,respectively, allowing about 98% to 2% of power to flow to the loadcompared to operation directly from the AC mains (AC line voltage (35)).Similarly, a reverse-phase modulated dimmer will provide an outputvoltage across a resistive load as illustrated in FIG. 4, which providesenergy to the load at the beginning of each cycle, such as from 0° to90°, for example, with no energy delivered in the latter part of eachcycle (illustrated as interval β).

Referring to FIG. 2, the firing angle α is determined by the RC timeconstant of capacitor 77 (C1), resistor 76 (R1), and the impedance ofthe load, such as an incandescent bulb or an LED driver circuit(Z_(LOAD) 81). In typical dimming applications, Z_(LOAD) will be ordersof magnitude lower than RI and resistive, thus will not affect thefiring angle appreciably. When the load is comparable to RI or is notresistive, however, the firing angle and behavior of the dimmer switchcan change dramatically.

Typical prior art, off-line AC/DC converters that drive LEDs using phasemodulation from a dimmer switch have several problems associated withproviding a quality drive to LEDs, such as: (1) phase modulation from adimmer switch can produce a low frequency (about 120 Hz) in the opticaloutput, referred to as “flicker,” which can be detected by a human eyeor otherwise create a reaction in people to the oscillating light; (2)filtering the input voltage may require quite a substantial value of theinput capacitor, compromising both the size of the converter and itsuseful life; (3) when the triac 80 is turned on, a large inrush currentmay be created, due to a low impedance of the input filter, which maydamage elements of both the dimmer switch 75 and any LED driver; and (4)power management controllers are typically not designed to operate in anenvironment having phase modulation of input voltage and couldmalfunction.

Accordingly, a need remains for an LED driver circuit which can operateconsistently with a typical or standard, forward or reverse,phase-modulating dimmer switch of the existing lighting infrastructureand avoid the problems discussed above, while providing theenvironmental and energy-saving benefits of LED lighting. Such an LEDdriver circuit should be able to be controlled by standard switches ofthe existing lighting infrastructure to provide the same regulatedbrightness, for example, for productivity, flexibility, aesthetics,ambience, and energy savings. An exemplary LED driver circuit should beable to operate not only alone, but also in parallel with other types oflighting, such as incandescent, compact fluorescent or other lighting,and be controllable by the same switches, for example, dimmer switchesor other adaptive or programmable switches used with such incandescentor other lighting. An exemplary LED driver circuit should also beoperable within the existing lighting infrastructure, without the needfor re-wiring or other retrofitting.

SUMMARY

The exemplary embodiments described herein provide numerous advantages.The exemplary embodiments allow for solid state lighting, such as LEDs,to be utilized with the currently existing lighting infrastructure,including Edison sockets, and to be controlled by any of a variety ofswitches, such as phase-modulating dimmer switches, which wouldotherwise cause significant operation problems for conventionalswitching power supplies or current regulators. The exemplaryembodiments further allow for sophisticated control of the outputbrightness or intensity of such solid state lighting, and may beimplemented using fewer and comparatively lower cost components. Inaddition, the exemplary embodiments may be utilized for stand-alonesolid state lighting systems, or may be utilized in parallel with othertypes of existing lighting systems, such as incandescent lamps.

Exemplary embodiments described herein not only recognize andaccommodate various states of switches, such as phase-modulating dimmerswitches, but further utilize a novel insight to also concurrentlyrecognize and accommodate various states of a switching power supply,such that both a phase-modulating dimmer switch and a switching powersupply operate together, seamlessly and with substantial stability. Moreparticularly, the exemplary embodiments recognize and accommodate atleast three states of a phase-modulating dimmer switch, namely, a firststate in which the dimmer switch is not conducting but during which atriggering capacitor (C1, 77) is charging; a second state in which thedimmer switch has turned on and requires a latching current; and a thirdstate in which the dimmer switch is fully conducting and requires aholding current. Concurrently, in combination with the states of theswitch, the exemplary embodiments recognize and accommodate at leastthree states, and in various embodiments four states, of a switchingpower supply, namely, a first, start-up state of the switching powersupply, during which it generates its power supply (V_(CC) voltagelevel); a second, gradual (graduated or “soft”) start state of theswitching power supply, during which it ramps up its provision of powerto a load (such as LEDs) (e.g., through pulse width modulation (“PWM”)switching) from start-up to a full operational mode; a third state,during which the switching power supply is in a full operational mode;and an optional fourth state, during which the switching power supplymay experience an abnormal or atypical operation and enter a protectiveoperating mode. For each combination of states of the switch (e.g.,dimmer switch) and switching power supply, using corresponding criteriafor stable operation, the exemplary embodiments provide a substantiallymatching electrical environment to meet such criteria for stableoperation of both the switch and the switching power supply, enablingseamless and stable operation of both components. In various exemplaryembodiments, the same type of substantially matching electricalenvironment may be utilized for multiple combinations of states, and inother instances, other types of substantially matching electricalenvironments will be utilized for a selected combination of states ofthe switch and switching power supply.

Exemplary embodiments described herein provide a method of interfacing aswitching power supply to a first switch coupled to an alternatingcurrent (AC) power source for providing power to solid state lighting.In various embodiments, the first switch is a forward or reversephase-modulated dimmer switch. An exemplary method comprises: sensing aninput current level; sensing an input voltage level; using a firstadaptive interface circuit, providing a resistive impedance to the firstswitch and conducting current from the first switch in a default mode;and using a second adaptive interface circuit, when the first switchturns on, creating a resonant process and providing a current pathduring the resonant process of the switching power supply.

In an exemplary embodiment, the method may further comprise: using thesecond adaptive interface circuit to modulate a current of the firstswitch during the resonant process of the switching power supply; and/orusing a third adaptive interface circuit to modulate a current of thefirst switch during the resonant process of the switching power supply;and/or using the first adaptive interface circuit to conduct currentduring a start-up state or a gradual start state of the switching powersupply; and/or using the first adaptive interface circuit to conductcurrent during charging of a trigger capacitor of the first switch,during turn on of the first switch, and during conduction of the firstswitch.

In various exemplary embodiments, the step of providing a resistiveimpedance may further comprise: switching the first adaptive interfacecircuit to provide a constant resistive impedance to the first switch;and/or modulating the first adaptive interface circuit to provide avariable resistive impedance to the first switch; and/or building anoperational voltage, and when the operational voltage has reached apredetermined level, modulating the first adaptive interface circuit andtransitioning to a gradual start of the switching power supplyasynchronously to the state of the first switch.

In various exemplary embodiments, the step of providing a current pathduring the resonant process may further comprise: determining a peakinput current level; and switching a resistive impedance to create thecurrent path. In other various exemplary embodiments, the step ofproviding a current path during the resonant process may furthercomprise: determining a peak input current level; and modulating aswitched, resistive impedance to create the current path.

In an exemplary embodiment, the method may further comprise: during afull power mode of the switching power supply and during charging of atrigger capacitor of the first switch, operating the switching powersupply at a one-hundred percent duty cycle or in a DC mode. In anotherexemplary embodiment, the method may further comprise: during a fullpower mode of the switching power supply and during turning on of thefirst switch, operating the switching power supply at a substantiallymaximum instantaneous power for a predetermined period of time.

In various exemplary embodiments, the second adaptive interface circuitcomprises an inductor in parallel with a resistor, and the method mayfurther comprise: during a full power mode of the switching power supplyand during turning on of the first switch, operating the switching powersupply at a substantially maximum instantaneous power until the inductorhas substantially discharged.

Also in various exemplary embodiments, the method may further comprise:using the second adaptive interface circuit to conduct current during afull operational power state of the switching power supply; and/oradjusting a minimum power from the first switch during a gradual startphase of the switching power supply.

In various exemplary embodiments, the second adaptive interface circuitfurther comprises a switchable resistive impedance, and the method mayfurther comprise: using the second adaptive interface circuit to providea current path during a start-up phase of the switching power supply,during a gradual start up of the switching power supply, or during afull operational mode of the switching power supply.

In an exemplary embodiment, the method may further comprise: using anoperational voltage bootstrap circuit coupled to the switching powersupply to generate an operational voltage. The first adaptive interfacecircuit may further comprise the operational voltage bootstrap circuit.

In various exemplary embodiments, the method may further comprise:determining a maximum duty cycle corresponding to the sensed inputvoltage level; providing a pulse width modulation operating mode for theswitching power supply using a switching duty cycle less than themaximum duty cycle; and when the duty cycle is within a predeterminedrange of the maximum duty cycle, providing a current pulse operatingmode for the switching power supply. In various exemplary embodiments,the method may further comprise: determining or obtaining from a memorya maximum duty cycle corresponding to the sensed input voltage level;and/or determining or varying the duty cycle to provide a predeterminedor selected average or peak output current level; and/or determining apeak output current level up to a maximum volt-seconds parameter.

In an exemplary embodiment, the method may further comprise: detecting amalfunction of the first switch. For example, the method may detect themalfunction by determining at least two input voltage peaks or two inputvoltage zero crossings during a half-cycle of the AC power source.

Other exemplary embodiments provide a system for power conversion, withthe system couplable to a first switch (such as a phase-modulated dimmerswitch) coupled to an alternating current (AC) power source, and withthe exemplary system comprising: a switching power supply comprising asecond power switch; solid state lighting coupled to the switching powersupply; a voltage sensor; a current sensor; a memory; a first adaptiveinterface circuit comprising a resistive impedance to conduct currentfrom the first switch in a default mode; a second adaptive interfacecircuit to create a resonant process when the first switch turns on; anda controller coupled to the voltage sensor, to the current sensor, tothe memory, to the second switch, to the first adaptive interfacecircuit and to the second adaptive interface circuit, and when the firstswitch turns on, the controller to modulate the second adaptiveinterface circuit to provide a current path during the resonant processof the switching power supply.

In various exemplary embodiments, the controller further is to modulatethe second adaptive interface circuit to modulate a current of the firstswitch during the resonant process of the switching power supply. In anexemplary embodiment, the system may further comprise: a third adaptiveinterface circuit to modulate a current of the first switch during theresonant process of the switching power supply.

In various exemplary embodiments, the controller further is to use thefirst adaptive interface circuit to conduct current during a start-upstate or a gradual start state of the switching power supply; and/or usethe first adaptive interface circuit to conduct current during chargingof a trigger capacitor of the first switch, during turn on of the firstswitch, and during conduction of the first switch; and/or switch thefirst adaptive interface circuit to provide a constant resistiveimpedance to the first switch; and/or modulate the first adaptiveinterface circuit to provide a variable resistive impedance to the firstswitch.

In an exemplary embodiment, when an operational voltage has reached apredetermined level, the controller further may modulate the firstadaptive interface circuit and transition to a gradual start of theswitching power supply asynchronously to the state of the first switch.In various exemplary embodiments, the second adaptive interface circuitcomprises a resistive impedance, wherein the controller further maydetermine a peak input current level, and when the peak input currentlevel has been reached, the controller further is to switch theresistive impedance to create the current path. In other variousexemplary embodiments, the second adaptive interface circuit comprises aswitched resistive impedance, wherein the controller further maydetermine a peak input current level, and when the peak input currentlevel has been reached, the controller further is to modulate theswitched, resistive impedance to create the current path.

In an exemplary embodiment, during a full power mode of the switchingpower supply and during charging of a trigger capacitor of the firstswitch, the controller further is to operate the switching power supplyat a one-hundred percent duty cycle or in a DC mode; and/or during afull power mode of the switching power supply and during turning on ofthe first switch, the controller further is to operate the switchingpower supply at a substantially maximum instantaneous power for apredetermined period of time. In another exemplary embodiment, thesecond adaptive interface circuit comprises an inductor in parallel witha resistor, and wherein during a full power mode of the switching powersupply and during turning on of the first switch, the controller furtheris to operate the switching power supply at a substantially maximuminstantaneous power until the inductor has substantially discharged.

In various exemplary embodiments, the controller further may use thesecond adaptive interface circuit to conduct current during a fulloperational power state of the switching power supply. In anotherexemplary embodiment, the controller further may adjust a minimum powerfrom the first switch during a gradual start phase of the switchingpower supply. In various exemplary embodiments, wherein the secondadaptive interface circuit further comprises a switchable resistiveimpedance, and wherein the controller further may use the secondadaptive interface circuit to provide a current path during a start-upphase of the switching power supply, during a gradual start up of theswitching power supply, or during a full operational mode of theswitching power supply.

In another exemplary embodiment, the system further comprises: anoperational voltage bootstrap circuit coupled to the switching powersupply to generate an operational voltage. In an exemplary embodiment,the first adaptive interface circuit further comprises the operationalvoltage bootstrap circuit.

In various exemplary embodiments, the controller further may determine amaximum duty cycle corresponding to the sensed input voltage level;provide a pulse width modulation operating mode for the switching powersupply using a switching duty cycle less than the maximum duty cycle;and when the duty cycle is within a predetermined range of the maximumduty cycle, provide a current pulse operating mode for the switchingpower supply. In various exemplary embodiments, the controller furthermay determine or obtain from a memory a maximum duty cycle correspondingto the sensed input voltage level; and/or may determine or vary the dutycycle to provide a predetermined or selected average or peak outputcurrent level. In an exemplary embodiment, the controller further maydetermine a peak output current level up to a maximum volt-secondsparameter.

In various exemplary embodiments, the controller further may detect amalfunction of the first switch, for example, by determining at leasttwo input voltage peaks or two input voltage zero crossings during ahalf-cycle of the AC power source.

In an exemplary embodiment, the first adaptive interface circuit maycomprise: a first resistor; a transistor coupled in series to the firstresistor, the transistor having a base or having a gate coupled to thecontroller; and a second resistor coupled to the base or to the gate ofthe transistor.

In another exemplary embodiment, the first adaptive interface circuitmay comprise: a first resistor; a transistor coupled in series to thefirst resistor, the transistor having a base or having a gate coupled tothe controller; a second resistor coupled to a source or an emitter ofthe transistor; and a zener diode coupled to the base or gate of thetransistor and coupled to the second resistor.

In an exemplary embodiment, the second adaptive interface circuit maycomprise: an inductor; and a resistor coupled in parallel to theinductor. In another exemplary embodiment, the second adaptive interfacecircuit may comprise: an inductor; a first resistor coupled to theinductor; a transistor having a base or a gate coupled to the firstresistor. In another exemplary embodiment, the second adaptive interfacecircuit may further comprise: a second resistor coupled to the inductorand coupled to a collector or drain of the transistor; a first zenerdiode coupled to an emitter or source of the transistor; and a seconddiode coupled to the inductor and to the first zener diode. In anotherexemplary embodiment, the second adaptive interface circuit maycomprise: an inductor; a first resistor; a differentiator; a one shotcircuit coupled to an output of the differentiator; and a transistorcoupled in series to the first resistor and further having a gate orbase coupled to an output of the one shot circuit.

In various exemplary embodiments, the solid state lighting is one ormore light-emitting diodes. The switching power supply may have anyconfiguration, such as having a non-isolated or an isolated flybackconfiguration. The system may have a form factor compatible with an A19standard, such as to fit within an Edison socket. The system may becouplable through a rectifier to the first switch. The system may becouplable through a rectifier and an inductor to the first switch.

In another exemplary embodiment, an apparatus is provided for powerconversion, the apparatus couplable to a first, phase-modulated dimmerswitch coupled to an alternating current (AC) power source, theapparatus couplable to a solid state lighting, and with the exemplaryapparatus comprising: a switching power supply comprising a second powerswitch; a voltage sensor; a current sensor; a memory; a first adaptiveinterface circuit comprising a resistive impedance to conduct currentfrom the first switch in a default mode; a second adaptive interfacecircuit to create a resonant process when the first switch turns on; anda controller coupled to the voltage sensor, to the current sensor, tothe memory, to the second switch, to the first adaptive interfacecircuit and to the second adaptive interface circuit, and when the firstswitch turns on, the controller to modulate the second adaptiveinterface circuit to provide a current path and to modulate a current ofthe first switch during the resonant process of the switching powersupply.

In another exemplary embodiment, a system is provided for powerconversion, the system having a form factor compatible with an A19standard, the system couplable to a phase-modulating dimmer switchcoupled to an alternating current (AC) power source, and with theexemplary system comprising: a switching power supply comprising a powerswitch; at least one light-emitting diode coupled to the switching powersupply; a voltage sensor to sense an input voltage level; a firstadaptive interface circuit to conduct current from the dimmer switch ina default mode, the first adaptive interface circuit further providing asubstantially matching impedance to the dimmer switch; a second adaptiveinterface circuit to create a resonant process of the switching powersupply and to provide a current path during the resonant process of theswitching power supply; a memory; and a controller coupled to the firstvoltage sensor, to the memory and to the power switch, the controller toprovide a pulse width modulation operating mode using a duty cycle lessthan a maximum duty cycle, and when the duty cycle is within apredetermined range of the maximum duty cycle, to provide a currentpulse operating mode.

Numerous other advantages and features will become readily apparent fromthe following detailed description, from the claims, and from theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, features, and advantages will be more readilyappreciated upon reference to the following disclosure when consideredin conjunction with the accompanying drawings, wherein like referencenumerals are used to identify identical components in the various views,and wherein reference numerals with alphabetic characters are utilizedto identify additional types, instantiations, or variations of aselected component embodiment in the various views, in which:

FIG. 1 is a circuit diagram illustrating a prior art current regulator;

FIG. 2 is a circuit diagram illustrating a representative prior artdimmer switch;

FIG. 3 is a graphical diagram illustrating the phase-modulated outputvoltage from a standard phase-modulated dimmer switch;

FIG. 4 is a graphical diagram illustrating the phase-modulated outputvoltage from a reverse phase-modulated dimmer switch;

FIG. 5 is a high-level block and circuit diagram illustrating ageneralized prior art current regulator (or converter);

FIG. 6 is a graphical diagram illustrating a triac voltage having asubharmonic startup frequency in a prior art current regulator coupledto a dimmer switch which causes perceptible LED flicker;

FIG. 7 is a graphical diagram illustrating a triac voltage with a 20KOhm load and illustrating premature startup in a prior art currentregulator coupled to a dimmer switch which causes perceptible LEDflicker;

FIG. 8 is a block diagram illustrating a first exemplary apparatusembodiment and a first exemplary system embodiment in accordance withthe teachings of the present disclosure;

FIG. 9 is a block diagram illustrating a second exemplary apparatusembodiment, a second exemplary system embodiment, and a second exemplaryadaptive interface embodiment in accordance with the teachings of thepresent disclosure;

FIG. 10 is a flow diagram illustrating a first exemplary methodembodiment in accordance with the teachings of the present disclosure;

FIG. 11 is a block and circuit diagram illustrating a third exemplaryapparatus embodiment, a third exemplary system embodiment, and a thirdexemplary adaptive interface embodiment in accordance with the teachingsof the present disclosure;

FIG. 12 is a block and circuit diagram illustrating a fourth exemplaryapparatus embodiment, a fourth exemplary system embodiment, and a fourthexemplary adaptive interface embodiment in accordance with the teachingsof the present disclosure;

FIG. 13 is a graphical timing diagram for exemplary switching of adimmer switch, an exemplary adaptive interface embodiment, powerprovided to an exemplary switching power supply, and exemplary adaptiveinterface power, in accordance with the teachings of the presentdisclosure;

FIG. 14 is a block and circuit diagram illustrating a fifth exemplaryapparatus embodiment, a fifth exemplary system embodiment, and a fifthexemplary adaptive interface embodiment in accordance with the teachingsof the present disclosure;

FIG. 15 is a block and circuit diagram illustrating a sixth exemplaryapparatus embodiment, a sixth exemplary system embodiment, and a sixthexemplary adaptive interface embodiment in accordance with the teachingsof the present disclosure;

FIG. 16 is a block and circuit diagram illustrating a seventh exemplaryapparatus embodiment, a seventh exemplary system embodiment, and aseventh exemplary adaptive interface embodiment in accordance with theteachings of the present disclosure;

FIG. 17 is a block and circuit diagram illustrating an eighth exemplaryapparatus embodiment and an eighth exemplary system embodiment inaccordance with the teachings of the present disclosure;

FIG. 18 is a flow diagram illustrating a second exemplary methodembodiment in accordance with the teachings of the present disclosure;

FIG. 19 is a flow diagram illustrating a third exemplary methodembodiment in accordance with the teachings of the present disclosure;

FIG. 20 is a graphical diagram illustrating exemplary transient voltageand current waveforms for a switch turn on in a resonant mode;

FIG. 21 is a graphical diagram illustrating exemplary, modeled transientvoltage and current waveforms for a fifth exemplary apparatusembodiment, a fifth exemplary system embodiment, and a fifth exemplaryadaptive interface embodiment in accordance with the teachings of thepresent disclosure;

FIG. 22 is a graphical diagram illustrating exemplary, modeled transientvoltage and current waveforms for a sixth exemplary apparatusembodiment, a sixth exemplary system embodiment, and a sixth exemplaryadaptive interface embodiment in accordance with the teachings of thepresent disclosure; and

FIG. 23 is a graphical diagram illustrating exemplary, modeled transientvoltage and current waveforms for a seventh exemplary apparatusembodiment, a seventh exemplary system embodiment, and a seventhexemplary adaptive interface embodiment in accordance with the teachingsof the present disclosure.

DETAILED DESCRIPTION

The present disclosure is not intended to limit the invention to thespecific embodiments illustrated. In this respect, it is to beunderstood that the invention is not limited in its application to thedetails of construction and to the arrangements of components set forthabove and below, illustrated in the drawings, or as described in theexamples. Methods and apparatuses consistent with the present inventionare capable of other embodiments and of being practiced and carried outin various ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract included below, arefor the purposes of description and should not be regarded as limiting.

As mentioned above, prior art LED driver circuits are often problematicwhen utilized with conventional dimmer switches 75, causing problemssuch as perceptible flicker and large inrush currents. For example, asillustrated in FIG. 5, a switching off-line LED driver 90 typicallyincludes a full wave rectifier 20 with a capacitive filter 15, whichallows current to flow to the filter capacitor (C_(FILT)) 15, when theinput voltage is greater than the voltage across the capacitor. Theinrush current to the capacitor is limited by the resistance in serieswith the capacitor. Under normal operating conditions, there may be aNegative Temperature Coefficient resistor (NTC) or thermistor in serieswith the capacitor to minimize inrush current during initial charging.This resistance will be significantly reduced during operation, allowingfor fast capacitor charging. This circuit will continuously peak chargethe capacitor to the peak voltage of the input waveform, 169 V DC forstandard 120 V AC line voltage.

When used with a dimmer switch 75, however, the charging current of thefilter capacitor is limited by the dimming resistance R1 (of resistor76) and is I_(CHARGE)=(V_(IN)−V_(LOAD)−V_(C1))/R1 (FIGS. 2 and 5). Thevoltage across the filter capacitor can be approximated to a DC voltagesource due to the large difference between C1 (77) and C_(FILT) (15).The charging current of the filter capacitor is also the chargingcurrent for C1, which controls the firing angle of the dimmer. Thecharging current for C1 will be decreased from normal dimmer operationdue to the large voltage drop (V_(C1)) across the filter capacitor 15.For large values of V_(C1), the current into C1 will be small and thusslowly charge. As a consequence, and as illustrated in FIG. 6, the smallcharging current may not be enough to charge C1 to the diac 85 breakovervoltage during one half cycle. If the breakover voltage is not reached(93), the triac 80 will not turn on. This will continue through manycycles until the voltage on the filter capacitor is small enough toallow C1 to charge to the breakover voltage. Once the breakover voltagehas been reached (94), the triac 80 will turn on and the capacitor willcharge to the peak value of the remaining half cycle input voltage. Thisphenomenon is illustrated in FIG. 6, requiring four cycles at 60 Hz (92)for this breakover voltage to be reached, such that the triac 80 onlyturns on at a subharmonic frequency, e.g., every 15 Hz as illustrated.

When a dimmer switch is used with a load drawing or sinking a smallamount of current, such that I_(LOAD) is less than the holding currentfor all values of the AC input, the triac 80 will provide inconsistentbehavior unsuitable for applications with LED drivers. The nominalfiring angle will increase due to the increased resistance of Z_(LOAD)81. When the capacitor (C1) voltage exceeds the diac breakover voltage,the diac 85 will discharge the capacitor into the gate of the triac 80,momentarily turning the triac on. Because the load resistance is toohigh to allow the necessary holding current, however, the triac 80 willthen turn off. When the triac turns off, the capacitor C1 beginscharging again through R1 and Z_(LOAD) (81). If there is enough timeremaining in the half cycle, the triac will fire again, and this processrepeats itself through each half cycle. Such premature and unsustainableon-states of a triac 80 are illustrated in FIG. 7, showing the multiplefirings (premature startup attempts) 91 of the triac 80 which can causeperceptible LED flicker.

For a prior art power supply in the normal status of operation, onecomparatively inefficient, prior art method to provide for sufficientcurrent through the dimmer switch 75 is to simply use a load resistor,R_(L), in parallel with (across) the dimmer switch 75, thereby providinga load current of at least V_(TRIAC)/R_(L) when the triac 80 is firing.By setting the resistor values small enough, the current can be madesufficiently high to ensure that it is above the threshold current(typically in the vicinity of 50 mA-100 mA) needed to keep the triac 80in an on-state. The power dissipation across the resistor R_(L) would beextremely high, i.e., 120²/R_(L) when the phase angle (firing angle α)is small, further resulting in creation of significant heat. Such a loadresistance is typically provided by an incandescent lamp, but is notautomatically provided by an electronic or switchable load, such as aswitching LED driver system.

Further, it is not always necessary to add more current to the triac 80when it is turning on, particularly if multiple lamps are being used(incandescent bulbs or LEDs) which are drawing sufficient current. Thus,in accordance with various exemplary embodiments, instead of a “dummy”resistor R_(L), active circuitry may be used which is capable ofadjusting according to the needs of the dimmer switch 75. The exemplaryembodiments provide current regulation to allow the triac 80 to switchon (fire) and to hold it in an on-state as desired. The exemplaryembodiments are also more power efficient, reducing the supplementedcurrent (and therefore I²R power loss) when there are other loadsproviding or sinking currents or when the phase angle α is small.

While solid state lighting (such as LED lighting) has significantenvironmental and energy-saving benefits, their adoption as the lightingtechnology of choice is less likely if they cannot be integrated into orotherwise made compatible for operation with the existing lightinginfrastructure. In accordance with the present disclosure, therefore, anLED driver circuit is provided which is compatible for operation withthe existing lighting infrastructure, such as dimmer switches, and maybe coupled directly to and controlled by such dimmer switches,regardless of whether other loads, such as additional incandescent orfluorescent lighting, are also coupled to and controlled by such dimmeror other switches. While the exemplary embodiments are illustrated anddiscussed below with reference to use with dimmer switches (75), itshould be noted that the exemplary embodiments are suitable for use witheffectively any types of switching devices or other lightinginfrastructure, except potentially those switches or otherinfrastructure specially designed or implemented for other purposes.

As indicated above, exemplary embodiments described herein not onlyrecognize and accommodate various states of switches, such asphase-modulating dimmer switches, but further utilize a novel insight toalso concurrently recognize and accommodate various states of aswitching power supply, such that both a phase-modulating dimmer switchand a switching power supply operate together, seamlessly and withsubstantial stability. More particularly, the exemplary embodimentsrecognize and accommodate at least three states of a phase-modulatingdimmer switch, namely, a first state in which the dimmer switch is notconducting but during which a triggering capacitor (C1, 77) is beingcharged; a second state in which the dimmer switch has turned on andrequires a latching current; and a third state in which the dimmerswitch is fully conducting and requires a holding current, such as for atriac (80) or thyristor. Concurrently, in combination with the states ofthe switch, the exemplary embodiments recognize and accommodate at leastthree states, and in various embodiments four states, of a switchingpower supply, namely, a first start-up state of the switching powersupply, during which it generates its power supply (V_(CC) voltagelevel); a second, gradual start state of the switching power supplyduring which it ramps up its provision of power to a load (such as LEDs)(e.g., through pulse width modulation switching) from start up to a fulloperational mode; a third state, during which the switching power supplyis in a full operational mode; and an optional fourth state, duringwhich the switching power supply may experience an abnormal or atypicaloperation and enter a protective operating mode. For each combination ofstates of the switch (e.g., dimmer switch) and switching power supply,using corresponding criteria for stable operation, the exemplaryembodiments provide a substantially matching electrical environment tomeet such criteria for stable operation of both the switch and theswitching power supply, enabling seamless and stable operation of bothcomponents. In various exemplary embodiments, the same type ofsubstantially matching electrical environment may be utilized formultiple combinations of states, and in other instances, other types ofsubstantially matching electrical environments will be utilized for aselected combination of states of the switch and switching power supply.

FIG. 8 is a block diagram of a first exemplary apparatus 100 embodiment,and a first exemplary system 105 embodiment in accordance with theteachings of the present disclosure. The apparatus 100 provides power toone or more LEDs 140, which may be an array or multiple arrays of LEDs140, of any type or color, with the apparatus 100 and LEDs 140 forming afirst system 105. The apparatus 100 is compatible with existing lightinginfrastructure, and may be coupled directly to a dimmer switch 75 forreceiving an AC voltage (potentially phase-modulated or without anymodulation) derived from the AC line voltage (AC mains) (35), and may beconstructed to fit within an A19 (e.g., Edison) socket, for example andwithout limitation. In addition, the apparatus 100 may operate inparallel with other or additional loads 95, such as an incandescent lampor other LEDs 140, under the common control of the dimmer switch 75.

More generally, the apparatus 100 may be utilized with any existinglighting infrastructure. In addition, it may not be known (such as by amanufacturer) in advance how the apparatus 100 and system 105 will bedeployed by the end user, so such compatibility with any existinglighting infrastructure is a true advantage of the exemplaryembodiments. For example, a manufacturer, distributor, or other providerof an apparatus 100 will typically not know in advance the types ofswitches to which the apparatus 100 and system 105 may be coupled (e.g.,to a dimmer switch 75, or a non-dimming switch), whether other loads 95may be present, and if so, what types of loads (e.g., incandescent, LED,fluorescent, etc.).

As illustrated, the apparatus 100 comprises one or more sensors 125, oneor more adaptive interfaces 115, a controller 120, a switching powersupply (or driver) 130, a memory (e.g., registers, RAM) 160, andtypically may also comprise a rectifier 110, depending on the type ofswitching power supply 130 utilized. Embodiments or otherimplementations for a controller 120 (and any of its variations, such as120A illustrated below) and a memory 160 are described in greater detailbelow. The one or more sensors 125 are utilized to sense or measure aparameter, such as a voltage or current level, with voltage sensors 125Aand current sensors 125B illustrated and discussed below. For purposesof the present disclosure, it may be assumed that a rectifier 110 ispresent, and those having skill in the art will recognize thatinnumerable other variations may be implemented, are equivalent, and arewithin the scope of the present disclosure. The switching power supply130 and/or the controller 120, in exemplary embodiments, may also andtypically will receive feedback from the LEDs 140, as illustrated. Oneor more adaptive interfaces 115 may be different types and may be placedin a wide variety of locations within the apparatus 100, depending uponthe selected embodiment, such as between the rectifier 110 and thedimmer switch 75, in addition to between the rectifier 110 and theswitching power supply 130, or in parallel with the switching powersupply 130, or within the switching power supply 130 (and moregenerally, an adaptive interface 115 may have any of the illustratedcircuit locations, such as in series or in parallel with the rectifieror switching power supply (or driver) 130, for example and withoutlimitation), as illustrated in FIG. 8. Exemplary adaptive interfaces 115and/or their components may be implemented generally using active orpassive components, or both. One or more sensors 125 also may bedifferent types and may be placed in a wide variety of locations withinthe apparatus 100, depending upon the selected embodiment, such asvoltage sensors 125A for detection of various input and/or outputvoltage levels, or current sensors 125B for detection of inductorcurrent levels (e.g., within switching power supply 130) and/or LED 140current, such as the various sensors 125 described in greater detailbelow. It should also be noted that the various components, such ascontroller 120, may be implemented in analog or digital form, and allsuch variations are considered equivalent and within the scope of thepresent disclosure. The rectifier 110 may be any type of rectifier,including without limitation, a full-wave rectifier, a full-wave bridge,a half-wave rectifier, an electromechanical rectifier, or another typeof rectifier as known or becomes known in the art. The apparatus 100 andsystem 105 also may be implemented in any form, including in formscompatible with A19 (Edison) or T8 sockets, for example.

In accordance with exemplary embodiments, dynamic control over the oneor more adaptive interfaces 115 is implemented, to account for both thecurrent state (or timing cycle) of the switching power supply 130 andthe current state (or timing cycle) of the dimmer switch 75, to providefor substantially stable operation of the apparatus 100 and system 105without incurring the various forms of flicker or other malfunctionsdiscussed above. Stated another way, a matching electrical (orelectronic) environment is provided for each state of the dimmer switch75 (non-conducting and charging a triggering capacitor, turning on witha latching current, and on and conducting with a holding current) inconjunction with each state of the switching power supply 130, such as astart-up state, a gradual or soft start power state, a full operationalmode power state, and a protective mode state. For example, assumingthat a dimmer switch 75 is installed and is not accessible directly toany sensing and functional manipulations, an exemplary method embodimentprovides for interfacing of a phase-modulated dimmer switch 75 and aswitching power supply 130 by controlling the functionality of theswitching power supply 130 in an adaptive timely manner whileconcurrently recognizing the current process in the dimmer switch 75,and providing a substantially matching electrical environment for astable completion of this dimmer 75 process and transition to anotherdimmer switch 75 process, such as transitioning from a charging processto a turning on process to a conducting process. Also for example andwithout limitation, a substantially matching electrical environment maybe provided by controlling the switching power supply 130 (e.g.,controlling a resonant process and current shaping), or by controllingan input impedance of the switching power supply 130, or controlling aninput current to the apparatus 100, or by controlling an input power ofthe switching power supply 130, including control by shutting down theswitching power supply 130.

FIG. 9 is a block diagram of a second exemplary apparatus embodiment100A, a second exemplary system embodiment 105A, and a second exemplaryadaptive interface embodiment 115A in accordance with the teachings ofthe present disclosure. In addition to the components previouslydiscussed with reference to the first exemplary apparatus embodiment100, the second exemplary apparatus embodiment is also illustrated asoptionally comprising filter capacitor 235, discussed in greater detailbelow. As illustrated in FIG. 9, an exemplary adaptive interface 115Acomprises one or more of five interface circuits, namely, a start-upinterface circuit 200, a gradual or soft start power interface circuit210, a full operation interface circuit 220, a resonant processinterface circuit 195, and a protective mode interface circuit 230. Inany selected embodiment, it should be noted that the five interfacecircuits 195, 200, 210, 220, and/or 230 may share common circuitry or beimplemented using the same circuitry, in addition to potentiallycomprising separate circuits, and may share common control parameters insome instances as well. While illustrated as located between a rectifier110 and the switching power supply 130, as discussed above, theexemplary adaptive interface 115A and/or its component interfaces 195,200, 210, 220, and/or 230 may have any of various circuit locationswithin an apparatus 100A, in addition to or in lieu of thoseillustrated.

As mentioned above, concerning the exemplary adaptive interface 115A, wecan distinguish at least four independent functional phases or states ofthe switching power supply 130, in conjunction with at least threeoperational states of a dimmer switch 75. The exemplary adaptiveinterface 115A recognizes and accommodates the various combinations ofstates of the dimmer switch 75 and the switching power supply 130 usingone or more of the component interfaces 195, 200, 210, 220, and/or 230.During switching power supply 130 start up, exemplary start-up interfacecircuit 200 is utilized for creating an operational voltage (V_(CC)) fora power supply controller 120, during which all other switching powersupply 130 circuits are disabled and energy consumption is comparativelysmall, and for providing or allowing sufficient current to the dimmerswitch 75 for any of its three states. During a gradual or soft startfor supplying power by the switching power supply 130, as an electricalprocess of supplying increasing levels of energy to the output load(LEDs 140), and energy consumption is comparatively small energy,gradual or soft start power interface circuit 210 is utilized to allowboth ramping up of output energy and sufficient current to the dimmerswitch 75 for any of its three states. During full operation of theswitching power supply 130, having nominal energy consumption, resonantprocess interface circuit 195 and full operation interface circuit 220are utilized to provide current shaping (generally controlling inputcurrent levels) and also allow sufficient current to the dimmer switch75 for any of its three states. A protective mode of operation, in whichthe switching power supply 130 or its various components are shut downand energy consumption is comparatively small, is also implemented usingprotective mode interface circuit 230, which, depending upon theselected embodiment, may also effectively shut down the dimmer switch 75or may allow sufficient current to the dimmer switch 75 for any of itsthree states.

By controlling the adaptive interface 115 and/or its componentinterfaces 195, 200, 210, 220 and/or 230, the various processes (orstates) of the dimmer switch 75 are also controlled, including withoutlimitation: (a) the charging of the triggering capacitor (C1) 77 andfiring of the diac (D1) 85 (and, in order to preserve the dimmer switch75 mechanical position (value of R1) related to the desired dimminglevel provided by the user, the external impedance of charging circuit(input impedance of the apparatus) is substantially close to oneprovided by an incandescent bulb (e.g., Z_(LOAD) 81), and no energy issupplied to the power supply); (b) turning on of the dimmer switch 75(e.g., triac 80) with a substantially minimum current nonethelesssufficient to exceed the triac 80 latching current, which involves atransient input to the apparatus 100 from zero power to any powersourced by AC line 35; and (c) conducting current through the dimmerswitch 75 (triac 80) through the end of the current AC cycle (e.g.,until zero voltage during the phase α, which may be referred toequivalently (although inexactly) as a zero crossing) with a current asmay be needed and nonetheless sufficient to exceed the triac 80 holdingcurrent with any power sourced by the AC line to the switching powersupply 130. For a reverse dimmer, the charging process ((a) above)generally follows the conducting process ((c) above), and those havingskill in the art will recognize the application of the exemplaryembodiments and principles taught herein to such situations.

FIG. 10 is a flow diagram of a first exemplary method embodiment inaccordance with the teachings of the present disclosure. The variousstates of the switching power supply 130 and the dimmer switch 75 may beviewed as forming a matrix, such that the functionality of the switchingpower supply 130 is controlled in a timely and adaptive manner,recognizing the current process of the dimmer switch 75, the currentstate of the switching power supply 130, and providing a correspondingsubstantially matching electrical environment for substantially stableoperation of the dimmer switch 75, the provision of appropriate power tothe LEDs 140, and the corresponding substantially stable transition fromstate to state. Referring to FIG. 10, the method begins with the turningon of the AC line, such as by a user mechanically turning on a dimmerswitch 75, start step 300. The apparatus 100, 100A (or the otherapparatus embodiments discussed below) (and/or the controller 120, 120A)then determines the functional status of the switching power supply 130,whether it is in any of the four states mentioned above, a protectivemode, full operational mode, gradual or soft start mode, or by defaultin a start-up mode (steps 302, 304, 306, and 308). For each of thesepossible states of the switching power supply 130, a state of the dimmerswitch 75 is determined (e.g., through one or more sensors 125) and acorresponding substantially matching electrical environment is providedfor the combination of states of both the switching power supply 130 andthe dimmer switch 75. Stated another way, for each of four states of theswitching power supply 130, one or more substantially matchingelectrical environments is provided when the triggering capacitor 77(C1) is being charged (steps 310, 316, 322, and/or 328), or when thedimmer switch 75 (triac 80) is turning on (steps 312, 318, 324, and/or330), or when current is being conducted through the dimmer switch 75(steps 314, 320, 326, and/or 332). Following steps 314, 320, 326, and/or332, the method determines whether the AC line (dimmer switch 75) hasbeen turned off, step 334, and if not, the method returns to step 302and iterates, and if so, the method may end, return step 336. As aconsequence, the apparatus 100, 100A (or the other apparatus embodimentsdiscussed below) provides a substantially matching electricalenvironment corresponding to both the state of the dimmer switch 75 andthe switching power supply 130. The various combinations of states,monitoring of states, and provision of substantially matching electricalenvironments is discussed in greater detail below.

For each of these 12 combinations of states or processes, and dependingon the intended deployment (e.g., 110 V, 220 V), correspondingparameters are predetermined and stored in memory 160, and then insubsequent operation, are retrieved from the memory 160 and utilized bythe controller 120 to provide the corresponding substantially matchingelectrical environment. As mentioned above, a substantially matchingelectrical environment may be provided by the controller 120 bycontrolling the switching power supply 130 (e.g., controlling a resonantprocess, current shaping, and other methods discussed below), or bycontrolling an input impedance of the switching power supply 130, orcontrolling an input current to the apparatus 100, or by controlling aninput power of the switching power supply 130, including control byshutting down the switching power supply 130, for example and withoutlimitation. It should be noted, however, that for various combinationsof states, the corresponding parameters and/or types of control may besubstantially similar of the same, depending on the selected embodiment.The corresponding parameters and/or types of control may be determinedin a wide variety of ways, such as based upon minimum voltage levels forany and/or all countries, component values, maximum voltage levels to betolerated by a switching power supply 130 and/or LEDs 140,characteristics of dimmer switches 75 (such as minimum holding andlatching currents), etc., with exemplary methods of predeterminingcorresponding parameters discussed in greater detail below. For exampleand without limitation, a minimum current parameter (e.g., 50 mA) may beutilized and sensed via a current sensor 125B, with a controller 120,120A then providing corresponding gating or modulation of the variousswitches and other circuits comprising an adaptive interface 115 toensure such minimum current flow. Accordingly, as the dimmer switch 75and switching power supply 130 change their respective functionalstatuses, the inventive method implemented by an apparatus 100, 100A-G(or the other apparatus embodiments discussed below) automaticallyadapts and adjusts using a new set of corresponding parameters for thecorresponding combination of states of the dimmer switch 75 andswitching power supply 130.

For example, a method of interfacing a power supply 130 powered througha dimmer switch 75 during the start-up state of an apparatus 100, 100A-G(switching power supply 130), by providing a substantially matchingelectrical environment, may comprise the following sequence (FIG. 10,steps 310-314):

-   -   1. Monitoring the status of the dimmer switch 75 (steps        310-314).    -   2. Recognizing that the dimmer switch 75 status is that of        charging its triggering capacitor 77 (step 310).    -   3. Providing a comparatively low impedance to the dimmer switch        75 (steps 310-314), thereby allowing sufficient current to flow        to charge the triggering circuitry, and further effectively        emulating an incandescent lamp. For example, the provided        impedance can be constant with a maximum value to create current        at dimmer switch 75 turn on slightly exceeding the latching and        holding current thresholds (steps 312-314). The matching        impedance, in the case of an available independent control        voltage, can be adaptive, changing its value based on triggering        circuit charge time to sink the current slightly over latching        and holding current thresholds, which may be correspondingly        defined at the values of instantaneous AC voltage at dimmer turn        on.    -   4. Sensing when the dimmer switch 75 is turned on and        conducting, and continuing to provide the matching impedance to        the dimmer switch 75 to sink current slightly over holding        current threshold (step 312).    -   5. Starting a process of building an operational voltage for the        apparatus 100, 100A-G (by active or passive circuits), such as        to provide an operating voltage (V_(CC)) to the controller 120.        The provided matching interface impedance(s) will remain        activated through this process which may take a few complete        sequential cycles of the dimmer switch 75, namely, charging the        triggering capacitor 77, turning the dimmer switch 75 (triac 80)        on and conducting current through the dimmer switch 75 (steps        310-314).    -   6. Monitoring the level of the operational voltage of the        apparatus 100, 100A-G.    -   7. At a power-on reset threshold voltage level, enabling the        controller 120 and transitioning to the gradual or soft start of        the switching power supply 130.    -   8. Continuing providing a matching impedance(s) to the dimmer        switch 75 to charge triggering capacitor, turn on the dimmer        switch 75 and adaptively sink sufficient current over the        latching and then holding current thresholds during the        transition to gradual or soft start (steps 310-314).

Accordingly, during start up of the apparatus 100, 100A-G and itsincorporated switching power supply 130, for any state of the dimmerswitch 75, an interface circuit (e.g., 115, 200, 210, and/or the othersdiscussed below) is utilized for providing an appropriate impedance toallow sufficient current for the corresponding state of the dimmerswitch 75, thereby generating a corresponding, substantially matchingelectrical environment for each combination of states.

FIG. 11 is a block and circuit diagram of a third exemplary apparatusembodiment 100B, a third exemplary system embodiment 105B, and a thirdexemplary adaptive interface embodiment 115B in accordance with theteachings of the present disclosure. Not separately illustrated, theapparatus 100B may be coupled to a dimmer switch 75 and an AC line 35 aspreviously illustrated in FIGS. 8 and 9. For example and withoutlimitation, the third exemplary adaptive interface embodiment 115B maybe utilized during start up, gradual or soft start and other processes(and states of the switching power supply 130), and may be utilized toimplement either or both a start-up interface circuit 200, a gradual orsoft start power interface circuit 210, and/or a full operationinterface circuit 220, for example and without limitation. Referring toFIG. 11, third exemplary adaptive interface embodiment 115B comprises aresistive impedance (resistor 202), switch 205 and optional resistor203, with the resistor 202 connected to the dimmer switch 75 (and inparallel with the switching power supply 130) by the switching of aswitch (depletion mode MOSFET) 205, which is on and conducting withoutthe provision of any control signal from the controller 120, providing acomparatively low impedance as a substantially matching electricalenvironment and further providing the comparatively low impedance as adefault mode, such as during V_(CC) generation (steps 310-314) or duringgradual or soft start (steps 316-320). Providing such a comparativelylow impedance as a default mode serves to ensure that the dimmer switch75 functions properly and has sufficient trigger capacitor charging,latching, and holding currents, provided through the resistive impedance(resistor 202) and switch 205, such as when the controller 120 andswitching power supply 130 are generating their respective operationalvoltages and may not yet be fully functional, e.g., when the dimmerswitch 75 is initially turned on by a user. If during this initialstart-up time interval the controller 120 has an independent voltagesource (such as a battery) or it develops an operational voltage, thecontroller 120 may change (adapt) this impedance to the optimalconditions for dimmer performance, as may be sensed by a voltage and/orcurrent sensor 125A, 125B. Following such start up, the controller 120may provide a control signal to the gate of the switch (MOSFET) 205,such as to modulate the current flow through resistor 202 and switch205, such as for gradual or soft start power mode of the switching powersupply 130, or to decrease or terminate the additional current flowthrough adaptive interface embodiment 115B, such as during fulloperational mode of the switching power supply 130 when sufficientcurrent may be drawn by the switching power supply 130. Those skilled inthe art, using principles of this disclosure, may suggest a variety ofother circuits to provide a comparatively low resistive impedance to thedimmer without any control signal for such a start-up process and adefault mode.

During gradual or soft start of the system 105B (FIG. 11), thecontroller 120 ramps up power to the load (LEDs) 140 compatible with thestable operation of the apparatus 100B (and other apparatuses 100, 100A,100C-G). Typically at or during gradual or soft start, the operatingswitching frequency, output voltage and output current are increasing. Asignificant parameter for the adaptive interface 115B is increasinginput power to the switching power supply 130 from levels below thematching of the minimum needs of the dimmer switch 75 to the levels farexceeding that minimum level to provide power to the LEDs 140. Anexemplary method of a gradual or soft start up of a switching powersupply 130 powered by a dimmer switch 75, by providing a substantiallymatching electrical environment to the dimmer switch 75, such as usinginterface 115B providing a resistive impedance, may comprise thefollowing sequence (FIG. 10, steps 316-320):

-   -   1. Transitioning from a start-up stage to a gradual or soft        start stage asynchronously to the state of the dimmer switch 75,        i.e., gradual or soft start may commence regardless of the state        of the dimmer switch 75, such as when the dimmer switch 75 is in        any one of its three cyclical states of charging its triggering        capacitor, turning on the dimmer switch 75, or conducting        current through the dimmer switch 75.    -   2. Continuing providing (via an adaptive interface 115) a        substantially matching electrical environment (as with the case        for the power supply 130 start up), such as using interface        115B, to keep the dimmer switch 75 operation stable in each of        its possible three states until the input voltage is        substantially zero (e.g., a zero crossing).    -   3. Monitoring the status of the dimmer switch 75 after a zero        crossing, such that if the dimmer switch 75 is off (a forward        dimmer), providing a matching resistive impedance to the        triggering circuit of the dimmer 75 via an adaptive interface        115, and if the dimmer switch 75 is on (a reverse dimmer),        providing a matching adaptive power sink to the dimmer via an        adaptive interface 115. The total matching power sink to the        dimmer switch 75 is equal to the sum of input power of the        switching power supply 130 and additional power consumed by an        adaptive interface 115. Exemplary matching adaptive power sinks        are discussed in greater detail below with reference to FIGS.        14-16.    -   4. Monitoring a change of the dimmer switch 75 status from        charging to turning on and conducting current for a forward        dimmer and providing a matching adaptive power sink to the        dimmer switch 75 via an adaptive interface 115 and providing a        matching resistive impedance to a triggering circuit of a        reverse dimmer.    -   5. Cyclically changing the dimmer matching electrical        environment compatible with and corresponding to the dimmer        switch 75 cyclical status.    -   6. Phasing the additional current drawn by an adaptive interface        115 to zero as input power of the switching power supply 130        increases and goes over a minimum level for ongoing stable        operation of the dimmer switch 75.    -   7. Transitioning to a full operation power mode and        discontinuing operations of applicable adaptive interfaces 115        as necessary or desirable.

Accordingly, during gradual or soft start of the apparatus 100, 100A-G,and its incorporated switching power supply 130, for any state of thedimmer switch 75, an interface circuit (e.g., 200, 210 and/or the othersdiscussed below) is utilized for providing an appropriate impedance toallow sufficient current for the corresponding state of the dimmerswitch 75 and to provide current shaping/control during dimmer turn on(as discussed in greater detail below), thereby generating acorresponding, substantially matching electrical environment for eachcombination of states. As the switching power supply 130 ramps up to afull operational mode, the additional current sinking provided by theadaptive interface 115 is decreased, while concurrently maintainingsufficient current through the dimmer switch for any of its charging,turning on, and conducting states.

FIG. 12 is a block and circuit diagram of a fourth exemplary apparatusembodiment 100C, a fourth exemplary system embodiment 105C, and a fourthexemplary adaptive interface embodiment 115C in accordance with theteachings of the present disclosure. Not separately illustrated, theapparatus 100C may be coupled to a dimmer switch 75 and an AC line 35 aspreviously illustrated in FIGS. 8 and 9. FIG. 13 is a graphical timingdiagram for exemplary switching of a dimmer switch, an exemplaryadaptive interface 115 embodiment, power provided to an exemplaryswitching power supply 130, and exemplary adaptive interface powerutilization, in accordance with the teachings of the present disclosure.For example and without limitation, the fourth exemplary adaptiveinterface embodiment 115C may be utilized during both start up andgradual or soft start processes for any state of the dimmer switch 75(steps 310-320), also may be utilized during full operational mode (step322), and may be utilized to implement either or both a start-upinterface circuit 200 and/or a gradual or soft start power interfacecircuit 210, for example and without limitation. The fourth exemplaryadaptive interface embodiment 115C comprises a matching resistiveimpedance 207 and 208 connected to the dimmer switch 75 by a switch(MOSFET) 215, to provide a substantially matching electrical environmentfor the dimmer switch 75 (for any of its three states) during start upand/or during gradual or soft start of the switching power supply 130.This matching resistive impedance can be either constant by using agate-to-source voltage defined by an optional zener diode 211, orvariable and driven by a control voltage from controller 120. The dimmerswitch 75 status is sensed by the voltage sensor 125A in this exemplaryembodiment. When the dimmer switch 75 is turning on, the controller 120regulates the current sink circuit formed by resistors 207, 208, 212,213, and switch (MOSFET) 215. The adaptive interface 115C is effectivelyregulating the input power to the system 105C such that the minimumcurrent to be put through the dimmer switch 75 for its stable operationis exceeded. As gradual or soft start of the switching power supply 130progresses to its full operational state and when the dimmer switch 75is on and conducting, the additional power consumed by an adaptiveinterface 115C is gradually phased out to zero, as illustrated in FIG.13.

Accordingly, during either start up or gradual or soft start states ofthe switching power supply 130, an adaptive interface 115, such as 115Bor 115C, provides a corresponding and substantially matching electricalenvironment to the dimmer switch 75, such as a constant or variableimpedance allowing sufficient current through the dimmer switch 75 to begreater than or equal to a latching or holding current (when the dimmeris turning on or is in an on-state, steps 312, 314, 318, and/or 320) andto provide a current path for charging the triggering capacitor (whenthe dimmer is in an off or non-conducting state, FIG. 10, steps 310,316). During full operational mode of the switching power supply 130,such a substantially matching electrical environment to the dimmerswitch 75, such as a constant or variable impedance, may also be used toprovide a current path for charging the triggering capacitor (when thedimmer is in an off or non-conducting state, FIG. 10, step 322).

A substantially matching electrical environment is also provided,actively (dynamically) or passively, during the full operational mode ofthe switching power supply 130. In various exemplary embodiments, aresonant mode is created for controlling an inrush, peak current whenthe dimmer switch 75 turns on, which is further actively modulated toavoid excessive current levels while concurrently maintaining minimumlatching and holding currents for the dimmer switch 75, as discussed ingreater detail below. Referring again to FIG. 9, an optional filtercapacitor 235 may be implemented to provide power factor correction, forexample. The filter capacitor 235 may be connected after the rectifier110 as illustrated, or between the rectifier 110 and the dimmer switch75. Inclusion of such a filter capacitor 235, however, can serve toextend and delay the charging time for the triggering capacitor 77.Various modeling has shown, for example, that a 3.4 ms delay forcharging the triggering capacitor 77 when connected to an incandescentbulb may be extended to 4.2 ms when such a filter capacitor 235 isutilized, potentially leading to non-triggering of the diac 85 due to alow voltage on triggering capacitor 77, even after one-half cycle ofcharging. To avoid undue delay in charging of the triggering capacitor77, in accordance with the exemplary embodiments, the capacitance of thefilter capacitor 235 should not exceed the capacitance of the triggeringcapacitor 77 by more than three orders of magnitude. In an exemplaryembodiment, the filter capacitor 235 is comparatively small, on theorder of about 0.5-2.5 μF, and more particularly on the order of aboutor substantially 0.1-0.2 μF in various exemplary embodiments, as alarger filter capacitor 235 would interfere with charging of thetriggering capacitor (77).

Use of such a comparatively small filter capacitor 235, however, withoutadditional components provided in the exemplary novel embodiments anddiscussed below, would allow for a substantial and potentially excessivepeak current into the switching power supply 130 when the dimmer switch75 is turned on, which may be harmful to the switching power supply 130,among other things. Accordingly, to avoid such a peak inrush current,exemplary embodiments create and modulate a resonant process during fulloperational mode of the switching power supply 130 when the dimmerswitch 75 is turning on (FIG. 10, step 324), such as by using anadaptive interface 115D, 115E, and/or 115F, as illustrated and discussedin greater detail below with reference to FIGS. 14-16 and FIGS. 20-23.Such creation and modulation of a resonant process may also be utilizedduring other states of the switching power supply 130 and dimmer switch75, such as during gradual or soft start when the dimmer switch 75 isturning on (step 318) and otherwise during the transition from gradualor soft start to full operational mode.

Exemplary apparatus 100B and 100C also comprise a voltage sensor 125Awhich may be utilized to sense the status of the dimmer switch 75.Alternatively, other types of sensors 125 may also be utilizedequivalently to determine the status of the dimmer switch 75. When thesensor 125 indicates that the dimmer switch 75 is off due to zerovoltage of a forward dimmer or the dimmer turning off for a reverse typeof dimmer, the voltage across the input filter capacitor 235 drops to avery small value. At about this time, during full operational mode, thecontroller 120 turns on at least one switch of the switching powersupply 130 (e.g., 285 in FIG. 17) which is series connected to the inputvia at least one magnetic winding (and as illustrated by the primarywinding of flyback transformer 280 in FIG. 17 or an inductor such asinductor 236 of FIGS. 14-16). Due to the comparatively small values ofthe capacitance of the filter capacitor 235 and inductance of inductorsin the switching power supplies working in the practical range offrequencies from 50 kHz to 1 MHz, the external impedance to charge thetriggering capacitor 77 is comparatively small and is in the range of anincandescent bulb value, thereby allowing sufficient current to chargethe triggering capacitor 77 (FIG. 10, step 322). Accordingly, duringfull operational mode and the transition to full operational mode fromgradual or soft start, during charging of the triggering capacitor 77,circuits within the switching power supply 130 may be utilized to ensuresufficient charging current (in addition to ensuring sufficient latchingand holding currents), without requiring additional resistive impedancesor current sinks, etc., to draw additional current for this purpose.

An exemplary first method of operating an apparatus having a switchingpower supply 130 and an input filter capacitor 235 (having acomparatively low capacitance, i.e., a small capacitor) during a fulloperation mode and when powered by a dimmer switch 75, by providing asubstantially matching electrical environment to the dimmer switch 75,may comprise the following sequence (FIG. 10, step 322):

-   -   1. Monitoring the status of the dimmer switch 75.    -   2. When the dimmer switch 75 has turned off, turning on the        primary switch of the switching power supply 130 in a first        switching mode with a substantially maximum practical duty cycle        (up to 100%) (FIG. 10, step 322) (and also effectively providing        an additional current path to allow charging of the triggering        capacitor, such as using an adaptive interface 115, as may be        necessary or desirable, for example, based on monitoring of        voltage or current levels (e.g., 115B, 115C)). For such charging        of the triggering capacitor during full operational mode, it        should be noted that components internal to the switching power        supply 130 may be utilized to provide the current path to allow        such charging, rather than other additional components.    -   3. Continuing switching the switching power supply 130 in the        first mode with the substantially maximum duty cycle if it less        than one-hundred percent (100%), or keeping it in a DC mode if        it is 100%.    -   4. When the dimmer switch 75 turns on, operating the switching        power supply 130 in a second switching mode having the duty        cycle determined by feedback from the switching power supply        130, such as via voltage or current sensors 125A, 125B, or        feedback from another circuit component, such as LED 140        current.

As mentioned above, a magnetic winding of some kind, such as an inductor236 or transformer, will be connected in series to the rectifier 110 atsome point during the switching cycle of the switching power supply 130.Inclusion of such a filter capacitor 235 and magnetic winding (inductor236) may serve to reduce the reliability of the performance of a dimmerswitch 75 without the introduction of a corresponding substantiallymatching electrical environment in accordance with the exemplaryembodiments, using methods in addition to those discussed for the startup and gradual or soft start functional phases of the switching powersupply 130, to provide for a more optimal performance of the switchingpower supply 130 during full operational mode (following gradual or softstart).

FIG. 20 is a graphical diagram illustrating exemplary voltage andcurrent waveforms for a switch turn on in a resonant mode if an inductoror other magnetic winding, without additional circuitry, is included,such as for the circuit of FIG. 14 if resistor 237 were not included(contrary to various exemplary embodiments). While the peak current 611and voltage 612 waveforms are damped oscillations and by including aninductor 236 are now below excessive current levels, during the timeinterval of t3 to t4, another problem may be created, as the illustratedmodeling indicates that dimmer switch 75 current is substantially zero,potentially resulting in a malfunction of the dimmer switch 75 andcausing perceptible flicker.

Various experimental modeling and theoretical analyses indicate,however, that with typical inductance and capacitance values of a priorart switching power supply, because the filter capacitor 235 is likelydischarged by the time the dimmer switch 75 turns on, the turning on ofthe dimmer switch 75 will produce transient voltage and current levelswhich may create an unstable, oscillatory interface with the dimmerswitch 75. To avoid such an unstable, oscillatory interface with thedimmer switch 75, a substantially matching electrical environment isintroduced in accordance with the exemplary embodiments, using anadaptive interface 115D which shapes or otherwise alters the currentprovided through the dimmer switch 75. FIG. 14 is a block and circuitdiagram of a fifth exemplary apparatus embodiment 100D, a fifthexemplary system embodiment 105D, and a fifth exemplary adaptiveinterface embodiment 115D in accordance with the teachings of thepresent disclosure. FIG. 21 is a graphical diagram illustratingexemplary, modeled transient voltage 616 and current 615 waveforms for afifth exemplary apparatus embodiment, a fifth exemplary systemembodiment, and a fifth exemplary adaptive interface embodiment inaccordance with the teachings of the present disclosure. Not separatelyillustrated, the apparatus 100D may be coupled to a dimmer switch 75 andan AC line 35 as previously illustrated in FIGS. 8 and 9. The adaptiveinterface 115D is an exemplary passive embodiment of a full operationinterface circuit 220, for example and without limitation. The adaptiveinterface 115D comprises a resistor 237 connected in parallel withinductor 236, and the inductor 236 and capacitor 235A form a resonantcircuit. When the resonant current reaches its peak, the voltage acrossthe inductor 236 changes polarity and partially discharges through theresistor 237, thereby diminishing the inrush current into the switchingpower supply 130 and preventing current to further charge filtercapacitor 235A, while simultaneously allowing sufficient latching andholding currents for the dimmer switch 75. Adaptive interface 115Dprovides a passive implementation of the method of interfacing of thedimmer switch 75 and switching power supply 130 by providing asubstantially matching electrical environment through shaping dimmerswitch 75 current in the resonant process and provides latching andholding currents well above any typical minimum value for a dimmerswitch 75. As illustrated in FIG. 21, experimental modeling indicatessignificant damping and effective elimination of any unwantedoscillation following switch turn on (waveform 613), and further mayprovide a minimum dimmer switch 75 current of about 96 mA (currentwaveform 615), a value above typical holding current levels (e.g., 50mA), while latching current has been shown to be about 782 mA, also wellabove the typical minimum latching current threshold.

In accordance with exemplary embodiments, the inductance and capacitancevalues of the resonant components outside the dimmer switch 75 (orotherwise a characteristic impedance, such as about the 250 Ohm valuementioned below) are predetermined or preselected in such way that thepeak resonant current both exceeds the value of the latching current ofthe dimmer switch 75 at any AC value at turn on, and further isreasonably or comparatively low in order to avoid damaging dimmer switch75 and switching power supply 130 components. For a 110 V (220 V)operating environment, one or more inductors having a combinedinductance of about 16-24 mH (40-50 mH), and more particularly 18-22 mH(43-47 mH), are utilized (e.g., three inductors implementing inductor236 at 6.8 mH each (15 mH each)), for the previously stated range ofcapacitance values for the filter capacitor 235, providing an overallcharacteristic impedance between about 200-300 Ohms, and moreparticularly, generally about 250 Ohms.

An exemplary second method of operating an apparatus 100, 100A-G havinga switching power supply 130 and an input filter capacitor 235 (having acomparatively low capacitance, i.e., a small capacitor) during a fulloperation mode and when powered by a dimmer switch 75, by providing asubstantially matching electrical environment to the dimmer switch 75when it has turned on, may comprise the following sequence (FIG. 10,step 326 or both steps 324-326):

-   -   1. Monitoring resonant current after dimmer switch 75 turn on.    -   2. When the resonant current has reached its peak, adaptively        providing a first interface mode using an adaptive interface 115        (e.g., 115E, 115F) as an additional transient path for the        current to divert it from resonant charging of the filter        capacitor 235 while simultaneously maintaining the dimmer switch        75 current above the holding (or latching) current threshold.    -   3. With the adaptive interface 115 (as an additional transient        circuit) activated, driving the switching power supply 130 with        the substantially maximum permissible instantaneous input power        without violation of the subsequent average power consumed by        the switching power supply 130 during the utility cycle as        determined or set by corresponding feedback.    -   4. Discontinuing use of the adaptive interface 115 and        transitioning to a second interface mode of the dimmer switch 75        and the switching power supply 130 at about the time the        resonant inductor has discharged its stored energy or when a        predetermined period of time has elapsed following the resonant        current having substantially reached its peak.

This exemplary methodology may be implemented, for example, using thecircuitry illustrated in FIGS. 15-17.

FIG. 15 is a block and circuit diagram of a sixth exemplary apparatusembodiment 100E, a sixth exemplary system embodiment 105E, and a sixthexemplary adaptive interface embodiment 115E in accordance with theteachings of the present disclosure. FIG. 22 is a graphical diagramillustrating exemplary, modeled transient voltage 621 and current 620,622 waveforms for a sixth exemplary apparatus embodiment, a sixthexemplary system embodiment, and a sixth exemplary adaptive interfaceembodiment in accordance with the teachings of the present disclosure.Not separately illustrated, the apparatus 100E may be coupled to adimmer switch 75 and an AC line 35, as previously illustrated in FIGS. 8and 9. The adaptive interface 115E implements a full operation interfacecircuit 220, for example and without limitation. The adaptive interface115E comprises inductor 236, resistors 238 and 239, switch (transistor)240, zener diode 241, and blocking diode 242. The inductor 236 andfilter capacitor 235A form a resonant circuit. A transistor 240 isconnected in series with the resistor 239 and diodes 241 and 242 across(in parallel with) the inductor 236. The base of transistor 240 is alsoconnected to the inductor 236 via a resistor 238. Blocking diode 242 andzener diode 241 prevent a turning on of the transistor 240 during thenon-resonant (or non-transient) switching cycles of the power supply130. When the resonant current through the dimmer switch 75 reaches itspeak, the polarity of the voltage across inductor 236 changes andtransistor 240 starts conducting, providing a transient current paththrough resistor 239 and preventing excessive overcharge of the filtercapacitor 235A. As illustrated in FIG. 22, experimental modeling(voltage waveform 621 across filter capacitor 235, modeled voltagewaveform 623 provided by dimmer switch 75, current 620 through dimmerswitch 75, and current 622 through transistor 240) indicates significantdamping and effective elimination of any unwanted oscillation, providingsubstantially stable operation of the dimmer switch 75, and furtherprovides both a maximum current of about 1.07 A and a minimum dimmerswitch 75 current of about 156 mA, a value above typical minimum holdingand latching current thresholds.

FIG. 16 is a block and circuit diagram of a seventh exemplary apparatusembodiment 100F, a seventh exemplary system embodiment 105F, and aseventh exemplary adaptive interface embodiment 115F in accordance withthe teachings of the present disclosure. FIG. 23 is a graphical diagramillustrating exemplary, modeled transient voltage and current waveformsfor a seventh exemplary apparatus embodiment, a seventh exemplary systemembodiment, and a seventh exemplary adaptive interface embodiment inaccordance with the teachings of the present disclosure. Not separatelyillustrated, the apparatus 100F may be coupled to a dimmer switch 75 andan AC line 35 as previously illustrated in FIGS. 8 and 9. The adaptiveinterface 115F implements a full operation interface circuit 220, forexample and without limitation. The adaptive interface 115F comprisesinductor 236, differentiator 261, one shot circuit 252, switch (MOSFETtransistor) 250, and resistor 251. A current sensor 125B is illustratedas embodied by and comprising a current sense resistor 260, which isillustrated as providing feedback to the differentiator 261 and alsooptionally to the controller 120. In addition to the other controlfunctionality of a controller 120 as discussed herein, controller 120Amay further comprise a differentiator 261. A voltage generated acrosscurrent sense resistor 260 may be utilized as an indicator of, forexample, current through the dimmer switch 75 (not separatelyillustrated). Inductor 236 and input filter capacitor 235A also form aresonant circuit as discussed above. A differentiator 261 comprisingoperational amplifier 255, capacitor 256, and resistors 253 and 254, isconnected (via capacitor 256 to its inverting input) to current senseresistor 260. The output of the differentiator 261 is coupled to a oneshot circuit 252 to drive the switch (MOSFET) 250 with a resistive load251. When the resonant current through the dimmer switch 75 reaches itspeak, the differentiator 261 triggers the one shot circuit 252 whichturns on switch (MOSFET) 250 for a predetermined or preselected timeduration, providing an additional path for current from inductor 236, toavoid additional charging of filter capacitor 235A. The variouswaveforms illustrated in FIG. 23 include current waveform 630 for thecurrent through the dimmer switch 75, voltage waveform 631 for thevoltage across the filter capacitor 235A, the input AC voltage waveform623 (when turned on by the dimmer switch 75), and the current waveform632 for the current through the MOSFET switch 250. Experimental modelingindicates significant damping and effective elimination of any unwantedoscillation, providing substantially stable operation of the dimmerswitch 75, and further may provide a minimum dimmer switch 75 current ofabout 100 mA, a value above typical minimum holding and latching currentthresholds, with resistor 251 and switch 250 sinking about 60 mA ofcurrent for a 1 A peak current, and with the on time duration of theswitch 250 (from the one shot circuit 252) being about 200 μs. Circuitryother than the one shot circuit 252 having a fixed active time durationcould be substituted equivalently, such as by a variable or dynamicactive time under the control of the controller 120, 120A, and thosehaving skill in the art may use numerous adaptive timing circuits toexercise such an option.

FIG. 17 is a block and circuit diagram of an eighth exemplary apparatusembodiment 100G and an eighth exemplary system embodiment 105G inaccordance with the teachings of the present disclosure. The apparatus100G implements both a full operation interface circuit 220 (usingadaptive interfaces 115D and 115F) and a combined start-up interface andgradual or soft start power interface circuit 200, 210 (using adaptiveinterface 115B, operating voltage bootstrap circuit 115G which alsofunctions as an adaptive interface), for example and without limitation.In addition, through the use of the various sensors 125 and thecontroller 120A (including the differentiator 261 for driving the oneshot circuit 252), the apparatus 100G also implements a protective modeinterface circuit 230, as discussed in greater detail below. Theapparatus 100G is considered exemplary of any of the variouscombinations of a resonant process interface circuit 195 (implementedusing interface 115D), a full operation interface circuit 220, astart-up interface 200, a gradual or soft start power interface circuit210, and a protective mode interface circuit 230, and those having skillin the electronic arts will recognize innumerable equivalentcombinations which are considered within the scope of the presentdisclosure.

As illustrated, the apparatus 100G comprises a controller 120A, a memory160 (e.g., registers, RAM), a plurality of sensors 125, a plurality ofadaptive interface circuits 115, optional coupling inductor 270 andcapacitor 271, a bridge rectifier 110A, filter capacitor 235A, bootstrapcircuit 115G for fast generation of an operating voltage V_(CC) (inblock 290) (and bootstrap circuit 115G also serves to operate as anadaptive interface circuit 115B, as discussed below), a switching powersupply 130A (illustrated as having a transformer 280 in a flybackconfiguration), and an optional resistance 295 (which may also functionas a voltage or current sensor in exemplary embodiments). The teachingsof this disclosure do not limit the topology of the apparatus 100G tothe referenced flyback configuration, and any type or kind of powersupply 130 configuration may be utilized, and may be implemented asknown or becomes known in the electronic arts. The apparatus 100G iscoupled to a dimmer switch 75 and an AC line 35 via inductor 270 andcapacitor 271, which are then coupled to a bridge rectifier 110A, as anillustration of an exemplary rectifier 110 which is coupled throughother components to the dimmer switch 75. The adaptive interface 115Band adaptive interface 115D function as discussed above to provide thesubstantially matching electrical environments to the dimmer switch 75during start up, gradual or soft start, and full operational modes. Adimmer status sensor 125C is also illustrated, which may be implementedusing any type of sensor, such as using a voltage sensor 125A asdiscussed above. As illustrated, a plurality of sensors 125 areutilized, in addition to the dimmer status sensor 125C, namely, twocurrent sensors 125B₁, 125B₂, and voltage sensor 125A. The apparatus100G provides power to one or more LEDs 140, which may be an array ormultiple arrays of LEDs 140, of any type or color, with the apparatus100G and LEDs 140 forming system 105G.

Exemplary embodiments or other implementations for a controller 120A anda memory 160 are described in greater detail below. The one or moresensors are utilized to sense or measure a parameter, such as a voltageor current level, and may be implemented as known or becomes known inthe electronic arts. The switching power supply 130A and/or thecontroller 120A may and typically will receive feedback from the LEDs140 via sensors 125A, 125B₁, 125B₂, as illustrated.

The adaptive interface circuits 115 of the apparatus 100G function asdiscussed previously. Bootstrap circuit 115G may be used both togenerate an operational voltage during start up and to provideadditional current sinking capability during any of the states of thedimmer switch 75. Switching of transistor 285 is utilized for deliveringpower to the plurality of LEDs 140 via transformer 280.

The controller 120A implements a first control method comprising twoparts, a pulse width modulation (PWM) switching of the switching powersupply 130A (via transistor 285), using a variable duty cycle (“D”) upto a maximum duty cycle (“D_(MAX)”), followed by an additional operatingmode, referred to as a current pulse mode, to maintain stable operationof the dimmer switch 75 and provide the appropriate dimming of the lightoutput. The duty cycle D is determined by the controller 120 based on adetected input voltage level, so that the apparatus 100G and system 105Gmay accommodate a wide range of input voltages (which may vary from timeto time and also both nationally and internationally, e.g., from 90 to130 V).

The output power P_(OUT) delivered by the switching power supply 130A tothe LEDs 140 is equal to:

$P_{OUT} = \frac{\pi\; V^{2}D}{4{fL}_{m}}$

where

-   -   V is the RMS input voltage;    -   D is the Duty cycle, averaged for a half cycle of the input AC        voltage;    -   f is the switching frequency of the power supply 130A; and    -   L_(m) is the magnetizing inductance of the transformer of the        switching power supply 130A.        For a constant switching frequency of the power supply 130A, the        duty cycle D is inversely proportional to the square of the        input voltage, i.e., when voltage is increasing the duty cycle        drops to deliver the same output power. Constant switching        frequency is given for an example only, and a method described        below is transparent to the frequency domain. Based on the        output power, a maximum duty cycle D_(MAX) is occurring at the        minimum input voltage. As a switching power supply 130 is        generally designed with a predetermined or otherwise certain        maximum duty cycle for a stable operation of its magnetic        components, the maximum duty cycle D_(MAX) is predetermined or        preselected at minimum input voltage. When the output of the        switching power supply 130 is controlled by a dimmer switch 75,        the controller 120 is configured to have an average duty cycle        based on an average input voltage regulated by the dimmer switch        75.

The following is an example to illustrate the insight of the presentdisclosure which introduces two separate control methodologies, withoutrelying solely on control through PWM as typically found in the priorart, in addition to independently controlling the amount of currentthrough the dimmer switch 75 to maintain stable operation. As anexample, at an input voltage of 90V RMS (Average 81 V), a D_(MAX)=0.6 isselected at a phase angle α=0. It should be noted that the maximumvolt-seconds (“voltsecs”) to magnetize the magnetic components (280)will happen at the crest of the input voltage. In the event that theinput voltage is or becomes 130 VRMs (average 120 V), the duty cycledeveloped, determined, or otherwise calculated by the controller 120decreases to D=0.29, and as for the same magnetizing voltsecs at thecrest of 130 V the duty cycle is D=0.415. As a consequence, working withD=0.415 is safe or otherwise appropriate for the magnetic components ofthe transformer 280. Assuming for this example that, at 130 V, the phasemodulation then introduced by the dimmer switch 75 is α=90°. The averageinput voltage will be 60V and controller 120 will generate a maximumpossible duty cycle D=D_(MAX)=0.6 to compensate for the lower inputvoltage. However, from the power supply 130A point of view, themagnetizing voltage at the crest still will be an amplitude of inputvoltage for which we calculated the maximum permissible duty cycle asD=0.415. The power supply 130A would then be forced to work at the crestwith an elevated duty cycle D=0.6 instead of D=0.415, which could meanthe saturation of the magnetic components (280) and power supply 130failure. Accordingly, recognizing that PWM alone will not accomplish thedesired stability under dimming conditions, to both draw sufficientcurrent for proper dimmer operation and provide the desired lightingoutput, the exemplary embodiments provide another, second controlmechanism for powering a switching power supply 130 from a dimmer switch75 for a stable interface of the dimmer switch 75 and switching powersupply 130.

A first control method is based on adjustment of the duty cycle based onaverage input voltage with maximum average duty cycle D_(MAX)preselected at minimum input voltage and stored in the controller 120A(or its memory or memory 160). For that predetermined or preselectedD_(MAX) value, another maximum parameter of the switching power supply130 is predetermined or otherwise preselected, namely, the maximumvolt-seconds (“VSEC_(MAX)”) at the crest or peak of the minimum inputvoltage and stored in the controller 120 (or its memory or memory 160).In accordance with various exemplary embodiments, the switching powersupply 130A is enabled to operate using a range of input voltages, whilethe operational duty cycle is maintained below D_(MAX) and the sameoperational volt-seconds are kept below maximum stored volt-secondsVSEC_(MAX). Accordingly, the switching power supply 130A operates with apotentially constant or adjustable duty cycle to generate a high powerfactor and it further switches to the volt-seconds limit whenever theduty cycle is excessive (i.e., within a predetermined range of D_(MAX))for the maximum preselected value of volt-seconds VSEC_(MAX).Implementation of this second inventive regulation mechanism of thefirst control method may be done by measuring input voltage andintegrating it (e.g., within the controller 120A, using an integrator,not separately illustrated) during the on time of the switch 285 of theswitching power supply 130A (and volt-seconds may also be obtainedthrough a feed forward technique, not shown on FIG. 17). It also can beimplemented by a switch current measurement, Ipeak control, using sensor125B₁ illustrated in FIG. 17. Rather than using a maximum volt-secondsVSEC_(MAX) parameter, another alternative control methodology for thesecond tier of this two-tiered control methodology will utilize a peakcurrent level (“I_(P)”) parameter, either the peak current level of theprimary inductor of transformer 280 or the output peak current level, toadjust the power provided to LEDs 140 under dimming conditions.

FIG. 18 is a flow diagram of a second exemplary method embodiment inaccordance with the teachings of the present disclosure, and provides auseful explanation and summary of the two-tiered control methodology,using either the maximum volt-seconds VSEC_(MAX) parameter or the peakcurrent level (“I_(P)”) parameter. Beginning with start step 400, themethod determines an input voltage, step 405. Using the determined orsensed input voltage, the method determines a duty cycle D for pulsewidth modulation, step 410, which is less than (or equal to) the maximumduty cycle D_(MAX), to provide the selected or predetermined averageoutput current level, I_(AV). The switching power supply is thenswitched using the duty cycle D, step 415, providing the selected orpredetermined average output current level, I_(AV). The method thendetermines whether the duty cycle D is within a predetermined range of(or substantially equal to) the maximum duty cycle D_(MAX), step 420,and if so, transitions to current pulse mode (step 425), and if not, andthe method is to continue (step 430), iteratively returns to step 405,adjusting the duty cycle D as may be needed based on the sensed inputvoltage to provide the selected or predetermined average output currentlevel, I_(AV), and continuing to provide PWM for the switching powersupply 130, 130A. When the duty cycle D is within the predeterminedrange of (or substantially equal to) the maximum duty cycle D_(MAX),current pulse mode is implemented, step 425, providing a current pulsewith a dynamically adjustable or varying peak current I_(P) (either thepeak current level of the primary inductor of transformer 280 or theoutput peak current level), to increase the output current level duringa selected interval, up to a maximum peak current level (“I_(MAX)”), tomaintain the output current (usually the selected or predeterminedaverage output current level, I_(AV)) above a predetermined or selectedminimum level, to maintain sufficient current for the LEDs 140 to emitlight, and simultaneously allow a dimming effect. Alternatively, in step425, current pulse mode is also implemented, step 425, providing acurrent pulse with a dynamically adjustable or varying peak currentI_(P) (either the peak current level of the primary inductor oftransformer 280 or the output peak current level), to increase theoutput current level during a selected interval, up to a maximumvolt-seconds VSEC_(MAX) parameter, to maintain the output current(usually the selected or predetermined average output current level,I_(AV)) above a predetermined or selected minimum level, to maintainsufficient current for the LEDs 140 to emit light, and simultaneouslyallow a dimming effect. When the method is to continue, step 430, themethod returns to step 405 and iterates, and otherwise, the method mayend, return step 435.

The duty cycle control, peak current control, and/or maximumvolt-seconds VSEC_(MAX) control is implemented by the controller 120,120A, which may dynamically increase or decrease the duty cycle D tomaintain a selected or predetermined average output current (“I_(AV)”),up to the maximum duty cycle D_(MAX). Accordingly, if or when theapparatus 100 (and any of its variations 100A-100G) and system 105 (andany of its variations 105A-105G) is coupled to a dimmer switch 75 andthe user adjusts the dimmer switch to provide dimming, the duty cycle isdynamically adjusted and increased up to the maximum duty cycle D_(MAX),after which point the average output current to LEDs 140 may begin todecrease, and the output light emission is dimmed. The controller 120,120A, however, will transition to the additional, current pulse mode,and maintain the allowable peak current (amplitude) (i.e., up to apredetermined or selected maximum peak current or maximum volt-secondsVSEC_(MAX) parameter) to support sufficient current to the LEDs 140 suchthat light continues to be provided, and does not become so low that theLEDs 140 effectively shut off and stop emitting light. In these variousembodiments, a dimmer switch 75 is automatically accommodated, withoutany need for additional or separate detection of such a dimmer. Asignificant advantage of the first control method is that no additionalcurrent is utilized and, therefore, there are no additionalcorresponding power losses as found in the prior art.

The controller 120, 120A also functions as an adaptive interface(circuit 230) to implement the protective mode of operation. Using anyof the various sensors 125, the controller may determine that whilethere is incoming power from a dimmer switch 75 or other switch, forexample and without limitation, the output current (e.g., through theLEDs) is too high (e.g., indicative of a short circuit), or too low ornonexistent (indicative of an open circuit), or may detect other faultswithin any of the other various components. In these circumstances, thecontroller 120, 120A may provide a low power mode, taking sufficientpower to maintain an on-state of circuitry such as the controller 120,or may determine to shut down the apparatus 100, 100A-G, and/or theswitching power supply 130 completely.

FIG. 19 is a flow diagram of a third exemplary method embodiment inaccordance with the teachings of the present disclosure, by keeping thedimmer switch 75 operating stably but just at the edge or border ofpotentially becoming unstable, such as by having flicker or othertriggering issues. For example, and as illustrated above in FIGS. 6 and7, there are a wide variety of types of dimmer instability or improperperformance, such as (without limitation): (1) the dimmer switch 75 doesnot turn on within a half cycle of AC (35) being provided; (2) thedimmer switch 75 turns on more than one time within a half cycle of theAC (35); (3) following a zero crossing and conducting, a forward dimmerswitch 75 does not turn off at a next AC line voltage zero crossing; (4)a reverse dimmer switch 75 does not turn on following the first AC zerocrossing; (5) the phase angle α is changing from one half cycle toanother with different signs of changes, suggestive of the existence ofoscillations. Stable operation of a dimmer switch 75 may becharacterized using opposing criteria, such as (without limitation): (1)the dimmer switch 75 turns on once during each half cycle; (2) thedimmer switch 75 turns off (on) at AC zero crossings; and/or (3) thephase angle α is changing monotonically. Using any of the varioussensors 125, the controller 120 may be utilized to detect any of thesefeatures of improper or proper operation, such as using a voltage sensor125A to detect the voltage changes indicative of the dimmer switch 75turning on multiple times during a half cycle, or not turning off at theappropriate time, for example and without limitation.

Referring to FIG. 19, the method begins, start step 500, with the system105 being powered on, such as by applying AC voltage 35 to the dimmerswitch 75, and with adaptive interface circuits 115 set to their defaultlevels as discussed above, step 505, such that sufficient current levelsare drawn through the dimmer switch 75. Voltage or current levels aremonitored, step 510. When the voltage or current levels indicate thepresence of a dimmer switch, step 515, the method determines whether thedimmer switch is functioning properly or improperly, such as bydetecting the presence of flicker, step 520. For example, a dimmerswitch 75 may be present and also functioning properly, due to, forexample, the presence of other loads in parallel with the system 105,with sufficient current being drawn by all of the loads to maintainproper operation of the dimmer switch 75. Further, different dimmerswitches 75 may function improperly (or properly) at different holdingor latching currents, such that some dimmer switches 75 may functionproperly and others improperly for the same LEDs 140 and, therefore, itmay be necessary or desirable to detect flickering. Accordingly, whenthe method determines that the dimmer switch 75 is functioningimproperly in step 520, such as by detecting the presence of flicker,the method regulates the current from the dimmer switch 75 duringselected intervals, step 525, such as through control of any of thevarious adaptive interface circuits discussed above, and also asdiscussed below.

Another alternative may be utilized to diminish power consumption. Whenno dimmer switch 75 is present in step 515, or is functioning properlyin step 520, the controller 120 may be utilized to decrease the current(and power) drawn by the adaptive interface circuits 115 in theirdefault modes, determining whether any adaptive interface circuits 115with power dissipation are active, step 530. If so, and if the dimmerswitch 75 has not exhibited instability, an active adaptive interfacecircuit 115 may be selected, its current parameters stored in memory 160(and returned to if the dimmer switch 75 subsequently exhibitsinstability), and its power dissipation reduced, step 535, such as byreducing the amount of current through an adaptive interface circuit115B, with these parameters stored as next parameters in memory 160, forexample. The method then returns to step 205 and iterates, continuing tomonitor voltage and/or current levels and provide current regulationaccordingly. Following steps 525, 530, or 535, when the method is tocontinue (step 540), the method returns to step 510 and iterates,continuing to monitor voltage and/or current levels and provide currentregulation accordingly, and otherwise (such as when the system 105 isturned off) the method may end, return step 545.

For example, in this exemplary methodology, using dimmer status sensor125C or a voltage sensor 125A, the exemplary apparatus 100G detects thepresence of a dimmer switch 75. When a dimmer switch 75 is detected, thecontroller 120 and one or more adaptive interface circuits (e.g., 115Band 115D or any other of the illustrated interface circuits) provide oneor more of the following substantially matching electrical environmentsto the dimmer switch 75: (1) a small matching impedance to the dimmerswitch 75 triggering circuit, using adaptive interface circuit 115Bcontrolled by controller 120; (2) supports greater than holding currentof the dimmer switch 75 when the bootstrap circuit 115G is active andcharging a V_(CC) capacitor (290), which thereby also constitutes anadaptive interface circuit 115 controlled by controller 120; (3) adjustsminimum power from the dimmer switch 75 at gradual or soft start of theswitching power supply 130, also using adaptive interface circuit 115Bcontrolled by controller 120; (4) provides a matching small impedance tothe dimmer switch 75 triggering circuit by keeping the duty cycle D (ofthe switching power supply 130) close to 1, also under control of thecontroller 120; and/or (5) shaping the current of the dimmer switch 75in the resonant process, using one or more of adaptive interfacecircuits 115D, 115E, 115F.

The controller 120, which may be embodied using one or a plurality ofcontrollers or other comparable circuits, is typically configured tocompare the sensed output voltage and current levels to correspondingpredetermined voltage and current values, which may be programmed andstored in memory 160, or which may be obtained from memory 160 (such asthrough a look up table) based upon other sensed values, such as sensedinput voltage levels. Following such comparisons, an error signal orerror level is determined, such as a difference between the sensed andpredetermined levels, and corresponding feedback provided, such as toincrease or decrease output voltage or current levels, in a first mode,through modulating the on-time (on-time pulse width) of the power switch285 at a selected switching frequency, or at a variable switchingfrequency, which is generally at a substantially higher frequency thanthe AC line frequency, and in a second mode, by modulating the peakcurrent levels.

Several novel features are implemented in the apparatus 100 (and any ofits variations 100A-100G), system 105 (and any of its variations105A-105G), and controller 120 embodiments. First, the adaptiveinterface circuits 115 independently enable operation with aphase-modulated dimmer switch 75, without unwanted flicker and prematurestart-up problems of the prior art. Second, the adaptive interfacecircuits 115 provide control based on a combination of both the state ofthe dimmer switch 75 and the state of the switching power supply 130.Third, a resonant mode is introduced with input current shaping orcontrol during dimmer switch 75 turn on. Fourth, a PWM control isimplemented, as a first part of a two-part control method, having adynamic and adjustable maximum duty cycle D_(MAX), based or dependent onthe (sensed) input voltage, having a theoretical dynamic range of zeroto one hundred eighty degrees, and accommodating a wide range ofpotentially varying input voltages. Fifth, a current pulse mode isimplemented, as a second part of the two-part control method, having avariable and dynamically adjustable peak current level, for either theprimary inductor peak current level or the output peak current level, orup to a maximum volt-seconds VSEC_(MAX) parameter.

Additional advantages of the exemplary embodiments are readily apparent.The exemplary embodiments allow for solid state lighting, such as LEDs,to be utilized with the currently existing lighting infrastructure andto be controlled by any of a variety of switches, such asphase-modulating dimmer switches, which would otherwise causesignificant operation problems. The exemplary embodiments further allowfor sophisticated control of the output brightness or intensity of suchsolid state lighting, and may be implemented using fewer andcomparatively lower-cost components. In addition, the exemplaryembodiments may be utilized for stand-alone solid state lightingsystems, or may be utilized in parallel with other types of existinglighting systems, such as incandescent lamps. The exemplary embodimentsessentially may work with any high impedance load and/or anythingdrawing comparatively low current through a dimmer switch.

The various methodologies described above may also be combined inadditional ways. For example, dimmer detection is not required, andinstead a series element may be programmed to switch at predeterminedintervals to accommodate a dimmer switch, or also as described abovewith reference to FIGS. 9 and 10, switching duty cycles may bedetermined from input parameters, such as sensed input voltage levels.In addition, when dimmer detection may be utilized, different strategiesare available, such as blocking current to prevent capacitors fromcharging, such as through a series current control element, or providingcurrent bypassing, such as through an adaptive current control element.

A wide variety of control methodologies and alternative adaptiveinterface circuits 115 have been illustrated to implement the proposedmethod of interfacing of a dimmer switch and switching power supply bymodulating dimmer current and further by shaping dimmer current in aresonant process. The present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the specific embodiments illustrated. In thisrespect, it is to be understood that the invention is not limited in itsapplication to the details of construction and to the arrangements ofcomponents set forth above and below, illustrated in the drawings, or asdescribed in the examples. Methods and apparatuses consistent with thepresent invention are capable of other embodiments and of beingpracticed and carried out in various ways.

Although the invention has been described with respect to specificembodiments thereof, these embodiments are merely illustrative and notrestrictive of the invention. In the description herein, numerousspecific details are provided, such as examples of electroniccomponents, electronic and structural connections, materials, andstructural variations, to provide a thorough understanding ofembodiments of the present invention. One skilled in the relevant artwill recognize, however, that an embodiment of the invention can bepracticed without one or more of the specific details, or with otherapparatus, systems, assemblies, components, materials, parts, etc. Inother instances, well-known structures, materials, or operations are notspecifically shown or described in detail to avoid obscuring aspects ofembodiments of the present invention. In addition, the various Figuresare not drawn to scale and should not be regarded as limiting.

Those having skill in the electronic arts will recognize that thevarious single-stage or two-stage converters may be implemented in awide variety of ways, in addition to those illustrated, such as flyback,buck, boost, and buck-boost, for example and without limitation, and maybe operated in any number of modes (discontinuous current mode,continuous current mode, and critical conduction mode).

Reference throughout this specification to “one embodiment,” “anembodiment,” or a specific “embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure and notnecessarily in all embodiments, and further, are not necessarilyreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics of any specific embodiment of thedisclosure may be combined in any suitable manner and in any suitablecombination with one or more other embodiments, including the use ofselected features without corresponding use of other features. Inaddition, many modifications may be made to adapt a particularapplication, situation, or material. It is to be understood that othervariations and modifications of the embodiments described andillustrated herein are possible in light of the teachings herein.

It will also be appreciated that one or more of the elements depicted inthe Figures can also be implemented in a more separate or integratedmanner, or even removed or rendered inoperable in certain cases, as maybe useful in accordance with a particular application. Integrally formedcombinations of components are possible. In addition, use of the term“coupled” herein, including in its various forms such as “coupling” or“couplable,” means and includes any direct or indirect electrical,structural, or magnetic coupling, connection or attachment, oradaptation or capability for such a direct or indirect electrical,structural, or magnetic coupling, connection, or attachment, includingintegrally formed components and components which are coupled via orthrough another component.

As used herein for purposes of the present disclosure, the term “LED”and its plural form “LEDs” should be understood to include anyelectroluminescent diode or other type of carrier injection- orjunction-based system which is capable of generating radiation inresponse to an electrical signal, including without limitation, varioussemiconductor- or carbon-based structures which emit light in responseto a current or voltage, light-emitting polymers, organic LEDs, and soon, including within the visible spectrum, or other spectra such asultraviolet or infrared, of any bandwidth, or of any color or colortemperature.

A “controller” or “processor” may be any type of controller orprocessor, and may be embodied as one or more controllers, configured,designed, programmed, or otherwise adapted to perform the functionalitydiscussed herein. As the term controller or processor is used herein, acontroller or processor may include use of a single integrated circuit(“IC”), or may include use of a plurality of integrated circuits orother components connected, arranged, or grouped together, such ascontrollers, microprocessors, digital signal processors (“DSPs”),parallel processors, multiple core processors, custom ICs, applicationspecific integrated circuits (“ASICs”), field programmable gate arrays(“FPGAs”), adaptive computing ICs, associated memory (such as RAM, DRAMand ROM), and other ICs and components. As a consequence, as usedherein, the term controller (or processor) should be understood toequivalently mean and include a single IC, or arrangement of custom ICs,ASICs, processors, microprocessors, controllers, FPGAs, adaptivecomputing ICs, or some other grouping of integrated circuits whichperform the functions discussed below, with associated memory, such asmicroprocessor memory or additional RAM, DRAM, SDRAM, SRAM, MRAM, ROM,FLASH, EPROM or E²PROM. A controller (or processor) (such as controller120), with its associated memory, may be adapted or configured (viaprogramming, FPGA interconnection, or hard-wiring) to perform themethodology, as discussed below. For example, the methodology may beprogrammed and stored, in a controller 120 with its associated memory(and/or memory 160) and other equivalent components, as a set of programinstructions or other code (or equivalent configuration or otherprogram) for subsequent execution when the processor is operative (i.e.,powered on and functioning). Equivalently, when the controller 120 isimplemented in whole or part as FPGAs, custom ICs and/or ASICs, theFPGAs, custom ICs or ASICs also may be designed, configured and/orhard-wired to implement described methodology. For example, thecontroller 120 may be implemented as an arrangement of controllers,microprocessors, DSPs and/or ASICs, collectively referred to as a“controller,” which are respectively programmed, designed, adapted, orconfigured to implement described methodology, in conjunction with amemory 160.

The memory 160, which may include a data repository (or database), maybe embodied in any number of forms, including within any computer orother machine-readable data storage medium, memory device, or otherstorage or communication device for storage or communication ofinformation, currently known or which becomes available in the future,including, but not limited to, a memory integrated circuit (“IC”), ormemory portion of an integrated circuit (such as the resident memorywithin a controller 120 or processor IC), whether volatile ornon-volatile, whether removable or non-removable, including withoutlimitation, RAM, FLASH, DRAM, SDRAM, SRAM, MRAM, FeRAM, ROM, EPROM, orE²PROM, or any other form of memory device, such as a magnetic harddrive, an optical drive, a magnetic disk or tape drive, a hard diskdrive, other machine-readable storage or memory media such as a floppydisk, a CDROM, a CD-RW, digital versatile disk (DVD) or other opticalmemory, or any other type of memory, storage medium, or data storageapparatus or circuit, which is known or which becomes known, dependingupon the selected embodiment. In addition, such computer-readable mediaincludes any form of communication media which embodiescomputer-readable instructions, data structures, program modules orother data in a data signal or modulated signal, such as anelectromagnetic or optical carrier wave or other transport mechanism,including any information delivery media, which may encode data or otherinformation in a signal, wired or wirelessly, including electromagnetic,optical, acoustic, RF or infrared signals, and so on. The memory 160 maybe adapted to store various look up tables, parameters, coefficients,other information and data, programs, or instructions, and other typesof tables such as database tables.

As indicated above, the controller 120 is programmed, using software anddata structures, for example, to perform described methodology.Technology described herein may be embodied as software which providessuch programming or other instructions, such as a set of instructionsand/or metadata embodied within a computer-readable medium, discussedabove. In addition, metadata may also be utilized to define the variousdata structures of a look up table or a database. Such software may bein the form of source or object code, by way of example and withoutlimitation. Source code further may be compiled into some form ofinstructions or object code (including assembly language instructions orconfiguration information). The software, source code, or metadata maybe embodied as any type of code, such as C, C++, SystemC, LISA, XML,Java, Brew, SQL and its variations (e.g., SQL 99 or proprietary versionsof SQL), DB2, Oracle, or any other type of programming language whichperforms the functionality discussed herein, including various hardwaredefinition or hardware modeling languages (e.g., Verilog, VHDL, RTL) andresulting database files (e.g., GDSII). As a consequence, a “construct,”“program construct,” “software construct,” or “software,” as usedequivalently herein, means and refers to any programming language, ofany kind, with any syntax or signatures, which provides or can beinterpreted to provide the associated functionality or methodologyspecified (when instantiated or loaded into a processor or computer andexecuted, including the controller 120, for example).

The software, metadata, or other source code and any resulting bit file(object code, database, or look up table) may be embodied within anytangible storage medium, such as any of the computer or othermachine-readable data storage media, as computer-readable instructions,data structures, program modules, or other data, such as discussed abovewith respect to the memory 160, e.g., a floppy disk, a CD-ROM, a CD-RW,a DVD, a magnetic hard drive, an optical drive, or any other type ofdata storage apparatus or medium, as mentioned above.

In the foregoing description and in the Figures, sense resistors areshown in exemplary configurations and locations; however, those skilledin the art will recognize that other types and configurations of sensorsmay also be used and that sensors may be placed in other locations.Alternate sensor configurations and placements are within the scope ofthe disclosure.

As used herein, the term “DC” denotes both fluctuating DC (such as isobtained from rectified AC) and constant voltage DC (such as is obtainedfrom a battery, voltage regulator, or power filtered with a capacitor).As used herein, the term “AC” denotes any form of alternating currentwith any waveform (sinusoidal, sine squared, rectified sinusoidal,square, rectangular, triangular, sawtooth, irregular, etc.) and with anyDC offset and may include any variation such as chopped or forward- orreverse-phase modulated alternating current, such as from a dimmerswitch.

With respect to sensors, we refer herein to parameters that “represent”a given metric or are “representative” of a given metric, where a metricis a measure of a state of at least part of the regulator or its inputsor outputs. A parameter is considered to represent a metric if it isrelated to the metric directly enough that regulating the parameter willsatisfactorily regulate the metric. For example, the metric of LEDcurrent may be represented by an inductor current because they aresimilar and because regulating an inductor current satisfactorilyregulates LED current. A parameter may be considered to be an acceptablerepresentation of a metric if it represents a multiple or fraction ofthe metric. It is to be noted that a parameter may physically be avoltage and yet still represent a current value. For example, thevoltage across a sense resistor “represents” current through theresistor.

In the foregoing description of illustrative embodiments and in attachedfigures where diodes are shown, it is to be understood that synchronousdiodes or synchronous rectifiers (for example, relays, MOSFETs, or othertransistors switched off and on by a control signal) or other types ofdiodes may be used in place of standard diodes within the scope of thepresent disclosure. Exemplary embodiments presented here generallygenerate a positive output voltage with respect to ground; however, theteachings of the present disclosure apply also to power converters thatgenerate a negative output voltage, where complementary topologies maybe constructed by reversing the polarity of semiconductors and otherpolarized components.

For convenience in notation and description, transformers such astransformer 280 are referred to as a “transformer,” although inillustrative embodiments, it behaves in many respects also as aninductor. Similarly, inductors can, under proper conditions, be replacedby transformers. We refer to transformers and inductors as “inductive”or “magnetic” elements, with the understanding that they perform similarfunctions and may be interchanged within the scope of the presentdisclosure.

Furthermore, any signal arrows in the drawings/Figures should beconsidered only exemplary, and not limiting, unless otherwisespecifically noted. Combinations of components of steps will also beconsidered within the scope of the present disclosure. The disjunctiveterm “or,” as used herein and throughout the claims that follow, isgenerally intended to mean “and/or,” having both conjunctive anddisjunctive meanings (and is not confined to an “exclusive or” meaning),unless otherwise indicated. As used in the description herein andthroughout the claims that follow, “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise. Also, as usedin the description herein and throughout the claims that follow, themeaning of “in” includes “in” and “on” unless the context clearlydictates otherwise.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the summary or in theabstract, is not intended to be exhaustive or to limit the invention tothe precise forms disclosed herein. From the foregoing, it will beobserved that numerous variations, modifications, and substitutions areintended and may be effected without departing from the spirit and scopeof the disclosure. It is to be understood that no limitation withrespect to the specific methods and apparatus illustrated herein isintended or should be inferred. It is, of course, intended to cover bythe appended claims all such modifications as fall within the scope ofthe claims.

The invention claimed is:
 1. A method of interfacing a switching powersupply to a first switch coupled to an alternating current (AC) powersource for providing power to solid state lighting, the methodcomprising: sensing an input current level; sensing an input voltagelevel; using a first adaptive interface circuit, providing a resistiveimpedance to the first switch, wherein the first adaptive interfacecircuit includes a resistor and a second switch configured to provide alow impedance to the first switch in a default mode and to conductcurrent from the first switch; and using a second adaptive interfacecircuit, when the first switch initially turns on, creating a resonantprocess of the switching power supply and providing a current pathduring the resonant process, wherein current flow through the secondswitch is modulated based on the sensed input current level or thesensed input voltage level.
 2. The method of claim 1, wherein the firstswitch is a phase-modulated dimmer switch.
 3. The method of claim 1,further comprising: using the second adaptive interface circuit tomodulate a current of the first switch during the resonant process ofthe switching power supply.
 4. The method of claim 1, furthercomprising: using a third adaptive interface circuit to modulate acurrent of the first switch during the resonant process of the switchingpower supply.
 5. The method of claim 1, further comprising: using thefirst adaptive interface circuit to conduct current during a start upstate or a gradual start state of the switching power supply.
 6. Themethod of claim 5, further comprising: using the first adaptiveinterface circuit to conduct current during charging of a triggercapacitor of the first switch, during turn on of the first switch, andduring conduction of the first switch.
 7. The method of claim 1, whereinsaid providing a resistive impedance to the first switch comprises:using a controller, switching the first adaptive interface circuit toprovide a constant resistive impedance to the first switch.
 8. Themethod of claim 1, wherein said providing a resistive impedance to thefirst switch comprises: using a controller, modulating the firstadaptive interface circuit to provide a variable resistive impedance tothe first switch.
 9. The method of claim 1, wherein said providing acurrent path during the resonant process comprises: using a controller,determining a peak input current level; and using the controller,switching the resistive impedance to create the current path.
 10. Themethod of claim 1, wherein said providing a current path during theresonant process comprises: using a controller, determining a peak inputcurrent level; and using the controller, modulating a switched,resistive impedance to create the current path.
 11. The method of claim1, further comprising: during a full power mode of the switching powersupply and during charging of a trigger capacitor of the first switch,operating the switching power supply at a one-hundred percent duty cycleor in a DC mode.
 12. The method of claim 1, further comprising: during afull power mode of the switching power supply and during turning on ofthe first switch, operating the switching power supply at asubstantially maximum instantaneous power for a predetermined period oftime.
 13. The method of claim 1, wherein the second adaptive interfacecircuit comprises an inductor in parallel with a resistor, and whereinthe method further comprises: during a full power mode of the switchingpower supply and during turning on of the first switch, operating theswitching power supply at a substantially maximum instantaneous poweruntil the inductor has substantially discharged.
 14. The method of claim1, further comprising: using the second adaptive interface circuit toconduct current during a full operational power state of the switchingpower supply.
 15. The method of claim 1, further comprising: adjusting aminimum power from the first switch during a gradual start phase of theswitching power supply.
 16. The method of claim 1, wherein the secondadaptive interface circuit further comprises a switchable resistiveimpedance, and wherein the method further comprises: using the secondadaptive interface circuit to provide a current path during a start upphase of the switching power supply, during a gradual start up of theswitching power supply, or during a full operational mode of theswitching power supply.
 17. The method of claim 1, further comprising:using an operational voltage bootstrap circuit coupled to the switchingpower supply to generate an operational voltage.
 18. The method of claim17, wherein the first adaptive interface circuit further comprises theoperational voltage bootstrap circuit.
 19. The method of claim 1,further comprising: using a controller, detecting a malfunction of thefirst switch.
 20. A method of interfacing a switching power supply to afirst switch coupled to an alternating current (AC) power source forproviding power to solid state lighting, the method comprising: sensingan input current level; sensing an input voltage level; using a firstadaptive interface circuit, providing a resistive impedance to the firstswitch and conducting current from the first switch in a default mode;and using a second adaptive interface circuit, when the first switchinitially turns on, creating a resonant process of the switching powersupply and providing a current path during the resonant process, whereinsaid providing a resistive impedance to the first switch includes:building an operational voltage; and when the operational voltage hasreached a predetermined level, modulating the first adaptive interfacecircuit and transitioning to a gradual start of the switching powersupply asynchronously to the state of the first switch.
 21. A method ofinterfacing a switching power supply to a first switch coupled to analternating current (AC) power source for providing power to solid statelighting, the method comprising: sensing an input current level; sensingan input voltage level; using a first adaptive interface circuit,providing a resistive impedance to the first switch and conductingcurrent from the first switch in a default mode; using a second adaptiveinterface circuit, when the first switch initially turns on, creating aresonant process of the switching power supply and providing a currentpath during the resonant process; using a controller, determining amaximum duty cycle corresponding to the sensed input voltage level;using the controller, providing a pulse width modulation operating modefor the switching power supply using a switching duty cycle less thanthe maximum duty cycle; and using the controller, when the switchingduty cycle is within a predetermined range of the maximum duty cycle,providing a current pulse operating mode for the switching power supply.22. The method of claim 21, further comprising: determining or obtainingfrom a memory the maximum duty cycle corresponding to the sensed inputvoltage level.
 23. The method of claim 21, further comprising:determining or varying the switching duty cycle to provide apredetermined or selected average or peak output current level.
 24. Themethod of claim 21, further comprising: determining a peak outputcurrent level up to a maximum voltseconds parameter.
 25. A method ofinterfacing a switching power supply to a first switch coupled to analternating current (AC) power source for providing power to solid statelighting, the method comprising: sensing an input current level; sensingan input voltage level; using a first adaptive interface circuit,providing a resistive impedance to the first switch and conductingcurrent from the first switch in a default mode; using a second adaptiveinterface circuit, when the first switch initially turns on, creating aresonant process of the switching power supply and providing a currentpath during the resonant process; and using a controller, detecting amalfunction of the first switch by determining at least two inputvoltage peaks or two input voltage zero crossings during a half-cycle ofthe AC power source.